cifs: Pass a pointer to virt_to_page() in cifsglob

Like the other calls in this function virt_to_page() expects
a pointer, not an integer.

However since many architectures implement virt_to_pfn() as
a macro, this function becomes polymorphic and accepts both a
(unsigned long) and a (void *).

Fix this up with an explicit cast.
Acked-by: Tom Talpey <tom@talpey.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

fs/cifs/cifsglob.h

@@ -2218,7 +2218,7 @@ static inline void cifs_sg_set_buf(struct sg_table *sgtable,
 		} while (buflen);
 	} else {
 		sg_set_page(&sgtable->sgl[sgtable->nents++],
-			    virt_to_page(addr), buflen, off);
+			    virt_to_page((void *)addr), buflen, off);
 	}
 }