media: hantro: Convert imx8m_vpu_g2_irq to helper

It turns out that imx8m_vpu_g2_irq() doesn't depend on any platform
specifics and can be used with other G2 platform drivers too.

Move it to common code.

Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>