media: mtk-vpu: Drop unnecessary call to platform_get_resource()

mtk_vpu_probe() calls platform_get_resource(pdev, IORESOURCE_IRQ, ..)
to check if IRQ resource exists and later calls
platform_get_irq(pdev, ..) to get the actual IRQ.

This patch drops an unnecessary call to platform_get_resource() and
checks the return value of platform_get_irq(pdev, ..) to make sure the
IRQ line is valid.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>