media: imx: imx7_mipi_csis: Avoid double get of wrap clock

The wrap clock is retrieved with the other clocks using
devm_clk_bulk_get(), and retrieved independently with a specific
devm_clk_get() call. The latter isn't needed, replace it with usage of
the wrap clock from the bulk array.

As the wrap clock is mandatory, simplify its usage further by removing
conditionals.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>