xtensa: move early_trap_init from kasan_early_init to init_arch

There may be other users for the early traps besides KASAN. Move call to
the early_trap_init from kasan_early_init. Protect init_exc_table
initializer with ifdef to make sure it builds on noMMU configurations.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/traps.h

@@ -64,8 +64,10 @@ void do_unhandled(struct pt_regs *regs);
 static inline void __init early_trap_init(void)
 {
 	static struct exc_table init_exc_table __initdata = {
+#ifdef CONFIG_MMU
 		.fast_kernel_handler[EXCCAUSE_DTLB_MISS] =
 			fast_second_level_miss,
+#endif
 	};
 	xtensa_set_sr(&init_exc_table, excsave1);
 }

arch/xtensa/kernel/setup.c

@@ -47,6 +47,7 @@
 #include <asm/smp.h>
 #include <asm/sysmem.h>
 #include <asm/timex.h>
+#include <asm/traps.h>
 
 #if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE)
 struct screen_info screen_info = {
@@ -242,6 +243,11 @@ void __init early_init_devtree(void *params)
 
 void __init init_arch(bp_tag_t *bp_start)
 {
+	/* Initialize basic exception handling if configuration may need it */
+
+	if (IS_ENABLED(CONFIG_KASAN))
+		early_trap_init();
+
 	/* Initialize MMU. */
 
 	init_mmu();

arch/xtensa/mm/kasan_init.c

@@ -14,7 +14,6 @@
 #include <linux/kernel.h>
 #include <asm/initialize_mmu.h>
 #include <asm/tlbflush.h>
-#include <asm/traps.h>
 
 void __init kasan_early_init(void)
 {
@@ -31,7 +30,6 @@ void __init kasan_early_init(void)
 		BUG_ON(!pmd_none(*pmd));
 		set_pmd(pmd, __pmd((unsigned long)kasan_early_shadow_pte));
 	}
-	early_trap_init();
 }
 
 static void __init populate(void *start, void *end)