drivers/block/z2ram: use ioremap_wt() instead of __ioremap(_PAGE_WRITETHRU)

_PAGE_WRITETHRU is a target specific flag. Prefer generic functions.
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/block/z2ram.c

@@ -190,8 +190,7 @@ static int z2_open(struct block_device *bdev, fmode_t mode)
 			vfree(vmalloc (size));
 		}
 
-		vaddr = (unsigned long) __ioremap (paddr, size, 
-						   _PAGE_WRITETHRU);
+		vaddr = (unsigned long)ioremap_wt(paddr, size);
 
 #else
 		vaddr = (unsigned long)z_remap_nocache_nonser(paddr, size);