arm: K3: Update _start instruction

On K3 family SoCs, once the ROM loads image on R5, M3 resets R5 and
expects to start executing from 0x0. In order to handle this ROM
updates the boot vector of R5 such that first 64 bytes of image load
address are mapped to 0x0.

In this case, it is SPL's responsibility to jump to the proper image
location. So, update the PC with address of reset vector(like how
other exception vectors are handled), instead of branching to reset.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>

arch/arm/lib/vectors.S

@@ -19,7 +19,11 @@
  * for the non-boot0 case or by a boot0-header.
  */
         .macro ARM_VECTORS
+#ifdef CONFIG_ARCH_K3
+	ldr     pc, _reset
+#else
 	b	reset
+#endif
 	ldr	pc, _undefined_instruction
 	ldr	pc, _software_interrupt
 	ldr	pc, _prefetch_abort
@@ -94,6 +98,7 @@ _start:
  *************************************************************************
  */
 
+	.globl  _reset
 	.globl	_undefined_instruction
 	.globl	_software_interrupt
 	.globl	_prefetch_abort
@@ -102,6 +107,9 @@ _start:
 	.globl	_irq
 	.globl	_fiq
 
+#ifdef CONFIG_ARCH_K3
+_reset:			.word reset
+#endif
 _undefined_instruction:	.word undefined_instruction
 _software_interrupt:	.word software_interrupt
 _prefetch_abort:	.word prefetch_abort