s390: allow to set gcc -mtune flag

Add a new Kconfig choice group which allows to configure how gcc should
tune the generated code (via -mtune option).
By default the -mtune parameter will match the -march parameter.

This is a rather large patch, but I wouldn't know how to make this shorter
unfortunately.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index ecc9d4f..874e6d6 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -43,6 +43,14 @@
 cflags-$(CONFIG_MARCH_Z196)   += -march=z196
 cflags-$(CONFIG_MARCH_ZEC12)  += -march=zEC12
 
+cflags-$(CONFIG_MARCH_G5_TUNE)		+= -mtune=g5
+cflags-$(CONFIG_MARCH_Z900_TUNE)	+= -mtune=z900
+cflags-$(CONFIG_MARCH_Z990_TUNE)	+= -mtune=z990
+cflags-$(CONFIG_MARCH_Z9_109_TUNE)	+= -mtune=z9-109
+cflags-$(CONFIG_MARCH_Z10_TUNE)		+= -mtune=z10
+cflags-$(CONFIG_MARCH_Z196_TUNE)	+= -mtune=z196
+cflags-$(CONFIG_MARCH_ZEC12_TUNE)	+= -mtune=zEC12
+
 #KBUILD_IMAGE is necessary for make rpm
 KBUILD_IMAGE	:=arch/s390/boot/image