powerpc: Remove SYNC on non 6xx

SYNC is usefull for Powerpc 601 only. On everything else,
SYNC is empty.

Remove it from code that is not made to run on 6xx.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/27951fa6c9a8f80724d1bc81a6117ac32343a55d.1601362098.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/head_40x.S

@@ -72,7 +72,6 @@ turn_on_mmu:
 	lis	r0,start_here@h
 	ori	r0,r0,start_here@l
 	mtspr	SPRN_SRR0,r0
-	SYNC
 	rfi				/* enables MMU */
 	b	.			/* prevent prefetch past rfi */
 

arch/powerpc/kernel/head_booke.h

@@ -176,7 +176,6 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 #endif
 	mtspr	SPRN_SRR1,r10
 	mtspr	SPRN_SRR0,r11
-	SYNC
 	RFI				/* jump to handler, enable MMU */
 99:	b	ret_from_kernel_syscall
 .endm

arch/powerpc/kernel/misc_64.S

@@ -365,7 +365,6 @@ _GLOBAL(kexec_smp_wait)
 
 	li	r4,KEXEC_STATE_REAL_MODE
 	stb	r4,PACAKEXECSTATE(r13)
-	SYNC
 
 	b	kexec_wait