MFD: allow cs5535-mfd to build on X86 only

Stephen ran into the following build error:

  drivers/mfd/cs5535-mfd.c:30:22: error: asm/olpc.h: No such file or directory

olpc.h exists only on x86 (and in the future, ARM).  Rather than
wrapping the include in an #ifdef, just change cs5535-mfd to only build
on x86.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndres Salomon <dilinger@queued.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/mfd/Kconfig

@@ -592,7 +592,7 @@ config AB3550_CORE
 config MFD_CS5535
 	tristate "Support for CS5535 and CS5536 southbridge core functions"
 	select MFD_CORE
-	depends on PCI
+	depends on PCI && X86
 	---help---
 	  This is the core driver for CS5535/CS5536 MFD functions.  This is
           necessary for using the board's GPIO and MFGPT functionality.