x86: Change MMIO addr in readN(addr)/writeN(addr, val) to pointer

On x86, change the type of the address parameter in
read8()/read16/read32()/write8()/write16()/write32() to be a
pointer, instead of unsigned long.

Change-Id: Ic26dd8a72d82828b69be3c04944710681b7bd330
Signed-off-by: Kevin Paul Herbert <kph@meraki.net>
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/7784
Tested-by: build bot (Jenkins)
diff --git a/src/device/oprom/realmode/x86.c b/src/device/oprom/realmode/x86.c
index 461cb06..919fd6d 100644
--- a/src/device/oprom/realmode/x86.c
+++ b/src/device/oprom/realmode/x86.c
@@ -80,7 +80,7 @@
 	memcpy((void *)0xfffd9, &ident, 7);
 
 	/* system model: IBM-AT */
-	write8(0xffffe, 0xfc);
+	write8((void *)0xffffe, 0xfc);
 }
 
 static int (*intXX_handler[256])(void) = { NULL };