lib: move GENERIC_IOMAP to lib/Kconfig

define GENERIC_IOMAP in a central location
instead of all architectures. This will be helpful
for the follow-up patch which makes it select
other configs. Code is also a bit shorter this way.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig
index 408b055..b3abfb0 100644
--- a/arch/cris/Kconfig
+++ b/arch/cris/Kconfig
@@ -19,10 +19,6 @@
 config ARCH_USES_GETTIMEOFFSET
 	def_bool n
 
-config GENERIC_IOMAP
-       bool
-       default y
-
 config ARCH_HAS_ILOG2_U32
 	bool
 	default n
@@ -52,6 +48,7 @@
 	select HAVE_IDE
 	select HAVE_GENERIC_HARDIRQS
 	select GENERIC_IRQ_SHOW
+	select GENERIC_IOMAP
 
 config HZ
 	int