fbdev: omap: Remove unnecessary print function dev_err()

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

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=1957
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Helge Deller <deller@gmx.de>