media: rockchip: rkisp1: allow separate interrupts

Depending on the per-soc implementation there can be one interrupt
for isp, mipi and capture events or separate per-event interrupts.

So simply check for the presence of a named "mi" interrupt
to differentiate between the two cases.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>