s390: add z13 code generation support

Allow to generate code that only runs on z13 machines.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 878e679..e742ec5 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -42,6 +42,7 @@
 mflags-$(CONFIG_MARCH_Z10)    := -march=z10
 mflags-$(CONFIG_MARCH_Z196)   := -march=z196
 mflags-$(CONFIG_MARCH_ZEC12)  := -march=zEC12
+mflags-$(CONFIG_MARCH_Z13)   := -march=z13
 
 aflags-y += $(mflags-y)
 cflags-y += $(mflags-y)
@@ -53,6 +54,7 @@
 cflags-$(CONFIG_MARCH_Z10_TUNE)		+= -mtune=z10
 cflags-$(CONFIG_MARCH_Z196_TUNE)	+= -mtune=z196
 cflags-$(CONFIG_MARCH_ZEC12_TUNE)	+= -mtune=zEC12
+cflags-$(CONFIG_MARCH_Z13_TUNE)	+= -mtune=z13
 
 #KBUILD_IMAGE is necessary for make rpm
 KBUILD_IMAGE	:=arch/s390/boot/image