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/score/Kconfig b/arch/score/Kconfig
index df169e8..455ce2d 100644
--- a/arch/score/Kconfig
+++ b/arch/score/Kconfig
@@ -4,6 +4,7 @@
        def_bool y
        select HAVE_GENERIC_HARDIRQS
        select GENERIC_IRQ_SHOW
+       select GENERIC_IOMAP
 
 choice
 	prompt "System type"
@@ -33,9 +34,6 @@
 config CPU_SCORE7
 	bool
 
-config GENERIC_IOMAP
-	def_bool y
-
 config NO_DMA
 	bool
 	default y