MIPS: Fix map_physmem for cached mappings

map_physmem should return a pointer that can be used by the CPU to
access the given memory - on MIPS simply returning the physical address
as it does prior to this patch doesn't achieve that. Instead return a
pointer to the memory within (c)kseg0, which matches up consistently
with the (c)kseg1 pointer that uncached mappings return via ioremap.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

arch/mips/include/asm/io.h

@@ -501,7 +501,7 @@ map_physmem(phys_addr_t paddr, unsigned long len, unsigned long flags)
 	if (flags == MAP_NOCACHE)
 		return ioremap(paddr, len);
 
-	return (void *)paddr;
+	return (void *)CKSEG0ADDR(paddr);
 }
 
 /*