ARM: 7170/2: fix compilation breakage in entry-armv.S

Fix compilation failure, when Thumb support is not enabled:

arch/arm/kernel/entry-armv.S: Assembler messages:
arch/arm/kernel/entry-armv.S:501: Error: backward ref to unknown label "2:"
arch/arm/kernel/entry-armv.S:502: Error: backward ref to unknown label "3:"
make[2]: *** [arch/arm/kernel/entry-armv.o] Error 1
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Reviewed-by: NDave Martin <dave.martin@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/entry-armv.S

@@ -497,7 +497,7 @@ ENDPROC(__und_usr)
 	.popsection
 	.pushsection __ex_table,"a"
 	.long	1b, 4b
-#if __LINUX_ARM_ARCH__ >= 7
+#if CONFIG_ARM_THUMB && __LINUX_ARM_ARCH__ >= 6 && CONFIG_CPU_V7
 	.long	2b, 4b
 	.long	3b, 4b
 #endif