media: rzg2l-cru: Use proper guard() in irq handler

media: rzg2l-cru: Use proper guard() in irq handler

The irq handler uses a scoped_guard() that covers the whole function
body.

Replace it with a more appropriate guard() and reduce the indentation.

Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>