media: ti-vpe: cal: Merge all status variables in IRQ handler

The cal_irq() function reads three IRQ status registers and stores their
values in three different variables. As each value is processed right
after reading the corresponding register, a single variable is enough.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>