ARM: msm: fix compilation flags for MSM_SCM

CONFIG_MSM_SCM uses the smc instruction, which with some
toolchains requires a ".arch_extension" directive.

Cc: David Brown <davidb@codeaurora.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: David Brown <davidb@codeaurora.org>
diff --git a/arch/arm/mach-msm/scm.c b/arch/arm/mach-msm/scm.c
index 232f97a..bafabb5 100644
--- a/arch/arm/mach-msm/scm.c
+++ b/arch/arm/mach-msm/scm.c
@@ -180,6 +180,9 @@
 			__asmeq("%1", "r0")
 			__asmeq("%2", "r1")
 			__asmeq("%3", "r2")
+#ifdef REQUIRES_SEC
+			".arch_extension sec\n"
+#endif
 			"smc	#0	@ switch to secure world\n"
 			: "=r" (r0)
 			: "r" (r0), "r" (r1), "r" (r2)