KVM: selftests: Fix build on on non-x86 architectures

Commit 9a400068 ("KVM: selftests: x86: Avoid using SSE/AVX
instructions") unconditionally added -march=x86-64-v2 to the CFLAGS used
to build the KVM selftests which does not work on non-x86 architectures:

  cc1: error: unknown value ‘x86-64-v2’ for ‘-march’

Fix this by making the addition of this x86 specific command line flag
conditional on building for x86.

Fixes: 9a400068 ("KVM: selftests: x86: Avoid using SSE/AVX instructions")
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/kvm/Makefile

@@ -244,11 +244,13 @@ CFLAGS += -Wall -Wstrict-prototypes -Wuninitialized -O2 -g -std=gnu99 \
 	-fno-stack-protector -fno-PIE -I$(LINUX_TOOL_INCLUDE) \
 	-I$(LINUX_TOOL_ARCH_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude \
 	-I$(<D) -Iinclude/$(ARCH_DIR) -I ../rseq -I.. $(EXTRA_CFLAGS) \
-	-march=x86-64-v2 \
 	$(KHDR_INCLUDES)
 ifeq ($(ARCH),s390)
 	CFLAGS += -march=z10
 endif
+ifeq ($(ARCH),x86)
+	CFLAGS += -march=x86-64-v2
+endif
 ifeq ($(ARCH),arm64)
 tools_dir := $(top_srcdir)/tools
 arm64_tools_dir := $(tools_dir)/arch/arm64/tools/