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/mainboard/via/epia-m850/devicetree.cb b/src/mainboard/via/epia-m850/devicetree.cb
index 0c21cc8..aa2db2a 100644
--- a/src/mainboard/via/epia-m850/devicetree.cb
+++ b/src/mainboard/via/epia-m850/devicetree.cb
@@ -38,7 +38,7 @@
 				register "have_isa_interrupts" = "0"
 				register "irq_on_fsb" = "1"
 				register "enable_virtual_wire" = "1"
-				register "base" = "0xfecc0000"
+				register "base" = "(void *)0xfecc0000"
 				device ioapic 2 on end
 			end
 		end
@@ -71,7 +71,7 @@
 				register "have_isa_interrupts" = "1"
 				register "irq_on_fsb" = "1"
 				register "enable_virtual_wire" = "1"
-				register "base" = "0xfec00000"
+				register "base" = "(void *)0xfec00000"
 				device ioapic 1 on end
 			end
 			#chip drivers/generic/generic	# DIMM 0 channel 1