[ARM] Add -march=all to assembly file build in arch/arm/boot/compressed

This allows assembly files to be crafted to cover all ARM CPU types
rather than erroring out on instructions only in later CPUs.  We
are careful in these files to only execute CPU specific code when
the CPU ID says we can.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/boot/compressed/Makefile

@@ -76,7 +76,7 @@ KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS))
 endif
 
 EXTRA_CFLAGS  := -fpic -fno-builtin
-EXTRA_AFLAGS  :=
+EXTRA_AFLAGS  := -Wa,-march=all
 
 # Supply ZRELADDR, INITRD_PHYS and PARAMS_PHYS to the decompressor via
 # linker symbols.  We only define initrd_phys and params_phys if the