x86: start annotating early ioremap pointers with __iomem

Impact: some new sparse warnings in e820.c etc, but no functional change.

As with regular ioremap, iounmap etc, annotate with __iomem.

Fixes the following sparse warnings, will produce some new ones
elsewhere in arch/x86 that will get worked out over time.

arch/x86/mm/ioremap.c:402:9: warning: cast removes address space of expression
arch/x86/mm/ioremap.c:406:10: warning: cast adds address space to expression (<asn:2>)
arch/x86/mm/ioremap.c:782:19: warning: Using plain integer as NULL pointer

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 5618a10..ac2abc8 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -82,9 +82,9 @@
 extern void early_ioremap_init(void);
 extern void early_ioremap_clear(void);
 extern void early_ioremap_reset(void);
-extern void *early_ioremap(unsigned long offset, unsigned long size);
-extern void *early_memremap(unsigned long offset, unsigned long size);
-extern void early_iounmap(void *addr, unsigned long size);
+extern void __iomem *early_ioremap(unsigned long offset, unsigned long size);
+extern void __iomem *early_memremap(unsigned long offset, unsigned long size);
+extern void early_iounmap(void __iomem *addr, unsigned long size);
 extern void __iomem *fix_ioremap(unsigned idx, unsigned long phys);