ARM: armv7: Make indirect vector addresses globl

Make indirect vectors addresses global, so they can be replaced by
various code that needs to do so. For example the MX6 PCI express
driver needs to temporarily replace data abort handler when reading
the config space.
Signed-off-by: NMarek Vasut <marex@denx.de>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Eric Nelson <eric.nelson@boundarydevices.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>

arch/arm/cpu/armv7/start.S

@@ -38,12 +38,19 @@ _irq:			.word _irq
 _fiq:			.word _fiq
 _pad:			.word 0x12345678 /* now 16*4=64 */
 #else
+.globl _undefined_instruction
 _undefined_instruction: .word undefined_instruction
+.globl _software_interrupt
 _software_interrupt:	.word software_interrupt
+.globl _prefetch_abort
 _prefetch_abort:	.word prefetch_abort
+.globl _data_abort
 _data_abort:		.word data_abort
+.globl _not_used
 _not_used:		.word not_used
+.globl _irq
 _irq:			.word irq
+.globl _fiq
 _fiq:			.word fiq
 _pad:			.word 0x12345678 /* now 16*4=64 */
 #endif	/* CONFIG_SPL_BUILD */