video: smscufx.c: local functions should not be exposed globally

Functions not referenced outside of a source file should be marked
static to prevent them from being exposed globally.

Quiets the sparse warnings:

warning: symbol 'ufx_handle_damage' was not declared. Should it be static?

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Steve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

drivers/video/smscufx.c

@@ -846,7 +846,7 @@ static void ufx_raw_rect(struct ufx_data *dev, u16 *cmd, int x, int y,
 	}
 }
 
-int ufx_handle_damage(struct ufx_data *dev, int x, int y,
+static int ufx_handle_damage(struct ufx_data *dev, int x, int y,
 	int width, int height)
 {
 	size_t packed_line_len = ALIGN((width * 2), 4);