[S390] config option for z9-109 code generation.

Add a kernel config option for the IBM System z9. This will produce
faster code on newer compilers using the -march=z9-109 option.

Signed-off-by: Christian Borntraeger <cborntra@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 74ef57d..5deb9f7 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -33,6 +33,7 @@
 cflags-$(CONFIG_MARCH_G5)   += $(call cc-option,-march=g5)
 cflags-$(CONFIG_MARCH_Z900) += $(call cc-option,-march=z900)
 cflags-$(CONFIG_MARCH_Z990) += $(call cc-option,-march=z990)
+cflags-$(CONFIG_MARCH_Z9_109) += $(call cc-option,-march=z9-109)
 
 #
 # Prevent tail-call optimizations, to get clearer backtraces: