media: imx7-mipi-csis: Propagate the error if clock enabling fails

Currently the return value from clk_bulk_prepare_enable() is checked,
but it is not propagate it in the case of failure.

Fix it and also move the error message to the caller of
mipi_csis_clk_enable().

Signed-off-by: Fabio Estevam <festevam@gmail.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+samsung@kernel.org>