media: vsp1: mask interrupts before enabling

VSP hardware could be used (e.g. by the bootloader) before driver load,
and some interrupts could be left in enabled and pending state. In this
case, setting up VSP interrupt handler without masking interrupts before
causes interrupt handler to be immediately called (and crash due to null
vsp->info dereference).

Fix that by explicitly masking all interrupts before setting the interrupt
handler. To do so, have to set the interrupt handler later, after hw
revision is already detected and number of interrupts to mask gets
known.

Based on patch by Koji Matsuoka <koji.matsuoka.xm@renesas.com> included
in the Renesas BSP kernel.

Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>