/dev/mem: Use more consistent data types

The xlate_dev_{kmem,mem}_ptr() functions take either a physical address
or a kernel virtual address, so data types should be phys_addr_t and
void *. They both return a kernel virtual address which is only ever
used in calls to copy_{from,to}_user(), so make variables that store it
void * rather than char * for consistency.

Also only define a weak unxlate_dev_mem_ptr() function if architectures
haven't overridden them in the asm/io.h header file.

Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/arch/s390/include/asm/io.h b/arch/s390/include/asm/io.h
index cd6b9ee..d22c2ee 100644
--- a/arch/s390/include/asm/io.h
+++ b/arch/s390/include/asm/io.h
@@ -13,9 +13,10 @@
 #include <asm/page.h>
 #include <asm/pci_io.h>
 
-void *xlate_dev_mem_ptr(unsigned long phys);
 #define xlate_dev_mem_ptr xlate_dev_mem_ptr
-void unxlate_dev_mem_ptr(unsigned long phys, void *addr);
+void *xlate_dev_mem_ptr(phys_addr_t phys);
+#define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
+void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr);
 
 /*
  * Convert a virtual cached pointer to an uncached pointer