This driver uses GENERIC_IRQ_CHIP, so it needs to select GENERIC_IRQ_CHIP to
avoid build error.

Fixes below build errors:
ERROR: "irq_alloc_domain_generic_chips" [drivers/gpu/ipu-v3/imx-ipu-v3.ko] undefined!
ERROR: "irq_gc_mask_clr_bit" [drivers/gpu/ipu-v3/imx-ipu-v3.ko] undefined!
ERROR: "irq_gc_mask_set_bit" [drivers/gpu/ipu-v3/imx-ipu-v3.ko] undefined!
ERROR: "irq_generic_chip_ops" [drivers/gpu/ipu-v3/imx-ipu-v3.ko] undefined!
ERROR: "irq_gc_ack_set_bit" [drivers/gpu/ipu-v3/imx-ipu-v3.ko] undefined!
ERROR: "irq_get_domain_generic_chip" [drivers/gpu/ipu-v3/imx-ipu-v3.ko] undefined!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>