video: fbdev: pxa3xx-gcu: Remove unnecessary print function dev_err()

The print function dev_err() is redundant because platform_get_irq()
already prints an error.

Eliminate the follow coccicheck warning:
./drivers/video/fbdev/pxa3xx-gcu.c:615:2-9: line 615 is redundant
because platform_get_irq() already prints an error

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Helge Deller <deller@gmx.de>