video: mb862xxfbdrv.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 'mb862xx_intr' was not declared. Should it be static?
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

drivers/video/mb862xx/mb862xxfbdrv.c

@@ -579,7 +579,7 @@ static ssize_t mb862xxfb_show_dispregs(struct device *dev,
 
 static DEVICE_ATTR(dispregs, 0444, mb862xxfb_show_dispregs, NULL);
 
-irqreturn_t mb862xx_intr(int irq, void *dev_id)
+static irqreturn_t mb862xx_intr(int irq, void *dev_id)
 {
 	struct mb862xxfb_par *par = (struct mb862xxfb_par *) dev_id;
 	unsigned long reg_ist, mask;