ARM: ux500: build hotplug.o for ARMv7-a

If we try to build this file in a multiplatform configuration with
ARMv6 enabled, gas complains about the dsb operation being undefined.
Adding -march=armv7-a is safe because that code is only ever run
on ux500, which is Cortex-A9.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

arch/arm/mach-ux500/Makefile

@@ -15,3 +15,5 @@ obj-$(CONFIG_MACH_MOP500)	+= board-mop500.o board-mop500-sdi.o \
 				board-mop500-audio.o
 obj-$(CONFIG_SMP)		+= platsmp.o headsmp.o
 obj-$(CONFIG_HOTPLUG_CPU)	+= hotplug.o
+
+CFLAGS_hotplug.o		+= -march=armv7-a