EFI, x86: fix function prototype

Fix function prototype in header file to match source code:

linux-next-20080807/arch/x86/kernel/efi_64.c:100:14: error: symbol 'efi_ioremap' redeclared with different type (originally declared at include2/asm/efi.h:89) - different address spaces
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

include/asm-x86/efi.h

@@ -86,7 +86,7 @@ extern u64 efi_call6(void *fp, u64 arg1, u64 arg2, u64 arg3,
 	efi_call6((void *)(efi.systab->runtime->f), (u64)(a1), (u64)(a2), \
 		  (u64)(a3), (u64)(a4), (u64)(a5), (u64)(a6))
 
-extern void *efi_ioremap(unsigned long addr, unsigned long size);
+extern void __iomem *efi_ioremap(unsigned long addr, unsigned long size);
 
 #endif /* CONFIG_X86_32 */