[S390] make arch/s390 subdirectories depend on config option

Only add subdirectories of arch/s390 to kbuild if their respective
config option is selected.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/Kbuild b/arch/s390/Kbuild
index ae4b010..9858476 100644
--- a/arch/s390/Kbuild
+++ b/arch/s390/Kbuild
@@ -1,6 +1,7 @@
-obj-y += kernel/
-obj-y += mm/
-obj-y += crypto/
-obj-y += appldata/
-obj-y += hypfs/
-obj-y += kvm/
+obj-y				+= kernel/
+obj-y				+= mm/
+obj-$(CONFIG_KVM)		+= kvm/
+obj-$(CONFIG_CRYPTO_HW)		+= crypto/
+obj-$(CONFIG_S390_HYPFS_FS)	+= hypfs/
+obj-$(CONFIG_APPLDATA_BASE)	+= appldata/
+obj-$(CONFIG_MATHEMU)		+= math-emu/