drm/armada: fix NULL pointer comparison warning

Replace direct comparisons to NULL i.e.
'x == NULL' with '!x'. As per coding standard.
Signed-off-by: Ravikant B Sharma <ravikant.s2@samsung.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

drivers/gpu/drm/armada/armada_debugfs.c

@@ -113,7 +113,7 @@ static int drm_add_fake_info_node(struct drm_minor *minor, struct dentry *ent,
 	struct drm_info_node *node;
 
 	node = kmalloc(sizeof(struct drm_info_node), GFP_KERNEL);
-	if (node == NULL) {
+	if (!node) {
 		debugfs_remove(ent);
 		return -ENOMEM;
 	}