media: hantro: add fallback handling for single irq/clk

Currently the driver expects that each irq/clk will have a name
specified.

A valid point was raised by the DT maintainers - when there is a single
interrupt line or clock - the names are not needed.

Keep the names within the drivers themselves, but don't use them when
only a single entry exists. Instead use:
 - num_clk == 1 - devm_clk_get(..., NULL)
 - num_irq == 1 - platform_get_irq(..., 0)

Suggested-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>