MIPS: Fix a warning for virt_to_page

Compiling mm/highmem.c gives a warning: passing argument 1 of
'virt_to_phys' makes pointer from integer without a cast

Fixed by casting to void*

Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7337/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/page.h

@@ -223,7 +223,8 @@ static inline int pfn_valid(unsigned long pfn)
 
 #endif
 
-#define virt_to_page(kaddr)	pfn_to_page(PFN_DOWN(virt_to_phys(kaddr)))
+#define virt_to_page(kaddr)	pfn_to_page(PFN_DOWN(virt_to_phys((void *)     \
+								  (kaddr))))
 
 extern int __virt_addr_valid(const volatile void *kaddr);
 #define virt_addr_valid(kaddr)						\