sh: HAVE_IOREMAP_PROT depends on MMU.

HAVE_IOREMAP_PROT enables an unconditional reference to
generic_access_phys(), which remains undefined in the nommu case.
As there's no point in supporting this there anyways, simply fix
up the dependency.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -12,7 +12,7 @@ config SUPERH
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_GENERIC_DMA_COHERENT
-	select HAVE_IOREMAP_PROT
+	select HAVE_IOREMAP_PROT if MMU
 	help
 	  The SuperH is a RISC processor targeted for use in embedded systems
 	  and consumer electronics; it was also used in the Sega Dreamcast