fbdev: mb862xx: Fix check of return value from irq_of_parse_and_map()

NO_IRQ is used to check the return of irq_of_parse_and_map().
On some architecture NO_IRQ is 0, on other architectures it is -1.
irq_of_parse_and_map() returns 0 on error, independent of NO_IRQ.
So use 0 instead of using NO_IRQ.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Helge Deller <deller@gmx.de>