ARM: tango: pass ARM arch level for smc.S

allmodconfig is broken by the addition of the -mcpu=cortex-a9
flag for smc.S:

arch/arm/mach-tango/smc.S:1:0: warning: switch -mcpu=cortex-a9 conflicts with -march=armv6k switch

This sets the flag in the same way that all other platforms
do, to fix the compile error.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-tango/Makefile

@@ -1,2 +1,3 @@
-asflags-y += -mcpu=cortex-a9
+plus_sec := $(call as-instr,.arch_extension sec,+sec)
+AFLAGS_smc.o		:=-Wa,-march=armv7-a$(plus_sec)
 obj-y += setup.o smc.o