Use zalloc instead of calloc(1, ...)

Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Marek Chalupa <mchqwerty@gmail.com>
diff --git a/src/compositor-drm.c b/src/compositor-drm.c
index a5b6eb7..9b4d4dc 100644
--- a/src/compositor-drm.c
+++ b/src/compositor-drm.c
@@ -348,8 +348,8 @@
 	if (fb)
 		return fb;
 
-	fb = calloc(1, sizeof *fb);
-	if (!fb)
+	fb = zalloc(sizeof *fb);
+	if (fb == NULL)
 		return NULL;
 
 	fb->bo = bo;