sparc32: Fix page_to_phys().

It doesn't account for phys_base like it should, fix by using
page_to_pfn().

While we're here, make virt_to_page() use pfn_to_page() as well, so we
consistently use the asm/memory-model.h abstractions instead of
open-coding memory model assumptions.

Tested-by: Kristoffer Glembo <kristoffer@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/include/asm/io_32.h b/arch/sparc/include/asm/io_32.h
index 93fe21e..679c750 100644
--- a/arch/sparc/include/asm/io_32.h
+++ b/arch/sparc/include/asm/io_32.h
@@ -8,7 +8,7 @@
 #include <asm/page.h>      /* IO address mapping routines need this */
 #include <asm/system.h>
 
-#define page_to_phys(page)	(((page) - mem_map) << PAGE_SHIFT)
+#define page_to_phys(page)	(page_to_pfn(page) << PAGE_SHIFT)
 
 static inline u32 flip_dword (u32 l)
 {