Makefile: relax arm test

Currently Makefile accepts only armv7l.* When building kvmtool under 32bit
personality on Aarch64 machines, uname -m reports "armv8l", so build fails.
We expect doing 32bit arm builds in Aarch64 to become standard the same way
people do i386 builds on x86_64 machines.

Make the sed test a little more greedy so armv8l becomes acceptable.

Acked-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/Makefile b/Makefile
index 1534e6f..7b17d52 100644
--- a/Makefile
+++ b/Makefile
@@ -103,7 +103,7 @@
 
 # Translate uname -m into ARCH string
 ARCH ?= $(shell uname -m | sed -e s/i.86/i386/ -e s/ppc.*/powerpc/ \
-	  -e s/armv7.*/arm/ -e s/aarch64.*/arm64/ -e s/mips64/mips/)
+	  -e s/armv.*/arm/ -e s/aarch64.*/arm64/ -e s/mips64/mips/)
 
 ifeq ($(ARCH),i386)
 	ARCH         := x86