media: dvbdev: fix the logic when DVB_DYNAMIC_MINORS is not set

When CONFIG_DVB_DYNAMIC_MINORS, ret is not initialized, and a
semaphore is left at the wrong state, in case of errors.

Make the code simpler and avoid mistakes by having just one error
check logic used weather DVB_DYNAMIC_MINORS is used or not.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202410201717.ULWWdJv8-lkp@intel.com/


Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/9e067488d8935b8cf00959764a1fa5de85d65725.1730926254.git.mchehab+huawei@kernel.org