LoongArch: Use the "jr" pseudo-instruction where applicable

Some of the assembly code in the LoongArch port likely originated
from a time when the assembler did not support pseudo-instructions like
"move" or "jr", so the desugared form was used and readability suffers
(to a minor degree) as a result.

As the upstream toolchain supports these pseudo-instructions from the
beginning, migrate the existing few usages to them for better
readability.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/kernel/fpu.S

@@ -153,7 +153,7 @@ SYM_FUNC_START(_save_fp)
 	fpu_save_csr	a0 t1
 	fpu_save_double a0 t1			# clobbers t1
 	fpu_save_cc	a0 t1 t2		# clobbers t1, t2
-	jirl zero, ra, 0
+	jr	ra
 SYM_FUNC_END(_save_fp)
 EXPORT_SYMBOL(_save_fp)
 
@@ -164,7 +164,7 @@ SYM_FUNC_START(_restore_fp)
 	fpu_restore_double a0 t1		# clobbers t1
 	fpu_restore_csr	a0 t1
 	fpu_restore_cc	a0 t1 t2		# clobbers t1, t2
-	jirl zero, ra, 0
+	jr	ra
 SYM_FUNC_END(_restore_fp)
 
 /*
@@ -216,7 +216,7 @@ SYM_FUNC_START(_init_fpu)
 	movgr2fr.d	$f30, t1
 	movgr2fr.d	$f31, t1
 
-	jirl zero, ra, 0
+	jr	ra
 SYM_FUNC_END(_init_fpu)
 
 /*
@@ -229,7 +229,7 @@ SYM_FUNC_START(_save_fp_context)
 	sc_save_fcsr a2 t1
 	sc_save_fp a0
 	li.w	a0, 0					# success
-	jirl zero, ra, 0
+	jr	ra
 SYM_FUNC_END(_save_fp_context)
 
 /*
@@ -242,10 +242,10 @@ SYM_FUNC_START(_restore_fp_context)
 	sc_restore_fcc a1 t1 t2
 	sc_restore_fcsr a2 t1
 	li.w	a0, 0					# success
-	jirl zero, ra, 0
+	jr	ra
 SYM_FUNC_END(_restore_fp_context)
 
 SYM_FUNC_START(fault)
 	li.w	a0, -EFAULT				# failure
-	jirl zero, ra, 0
+	jr	ra
 SYM_FUNC_END(fault)

arch/loongarch/kernel/genex.S

@@ -28,7 +28,7 @@ SYM_FUNC_START(__arch_cpu_idle)
 	nop
 	idle	0
 	/* end of rollback region */
-1:	jirl	zero, ra, 0
+1:	jr	ra
 SYM_FUNC_END(__arch_cpu_idle)
 
 SYM_FUNC_START(handle_vint)
@@ -91,5 +91,5 @@ SYM_FUNC_END(except_vec_cex)
 
 SYM_FUNC_START(handle_sys)
 	la.abs	t0, handle_syscall
-	jirl    zero, t0, 0
+	jr	t0
 SYM_FUNC_END(handle_sys)

arch/loongarch/kernel/head.S

@@ -32,7 +32,7 @@ SYM_CODE_START(kernel_entry)			# kernel entry point
 	/* We might not get launched at the address the kernel is linked to,
 	   so we jump there.  */
 	la.abs		t0, 0f
-	jirl		zero, t0, 0
+	jr		t0
 0:
 	la		t0, __bss_start		# clear .bss
 	st.d		zero, t0, 0
@@ -86,7 +86,7 @@ SYM_CODE_START(smpboot_entry)
 	ld.d		tp, t0, CPU_BOOT_TINFO
 
 	la.abs	t0, 0f
-	jirl	zero, t0, 0
+	jr	t0
 0:
 	bl		start_secondary
 SYM_CODE_END(smpboot_entry)

arch/loongarch/mm/page.S

@@ -32,7 +32,7 @@ SYM_FUNC_START(clear_page)
 	st.d     zero, a0, -8
 	bne      t0,   a0, 1b
 
-	jirl     zero, ra, 0
+	jr       ra
 SYM_FUNC_END(clear_page)
 EXPORT_SYMBOL(clear_page)
 
@@ -79,6 +79,6 @@ SYM_FUNC_START(copy_page)
 	st.d     t7, a0,  -8
 
 	bne      t8, a0, 1b
-	jirl     zero, ra, 0
+	jr       ra
 SYM_FUNC_END(copy_page)
 EXPORT_SYMBOL(copy_page)

arch/loongarch/mm/tlbex.S

@@ -198,7 +198,7 @@ nopage_tlb_load:
 	dbar	0
 	csrrd	ra, EXCEPTION_KS2
 	la.abs	t0, tlb_do_page_fault_0
-	jirl	zero, t0, 0
+	jr	t0
 SYM_FUNC_END(handle_tlb_load)
 
 SYM_FUNC_START(handle_tlb_store)
@@ -366,7 +366,7 @@ nopage_tlb_store:
 	dbar	0
 	csrrd	ra, EXCEPTION_KS2
 	la.abs	t0, tlb_do_page_fault_1
-	jirl	zero, t0, 0
+	jr	t0
 SYM_FUNC_END(handle_tlb_store)
 
 SYM_FUNC_START(handle_tlb_modify)
@@ -525,7 +525,7 @@ nopage_tlb_modify:
 	dbar	0
 	csrrd	ra, EXCEPTION_KS2
 	la.abs	t0, tlb_do_page_fault_1
-	jirl	zero, t0, 0
+	jr	t0
 SYM_FUNC_END(handle_tlb_modify)
 
 SYM_FUNC_START(handle_tlb_refill)