staging: gpib: cec: Handle gpib_register_driver() errors

staging: gpib: cec: Handle gpib_register_driver() errors

The function gpib_register_driver() can fail and result in a
semi-registered module and does not return an error value if it
fails.

Unregister the pci registering function in case gpib_register_driver()
fails and return the error value. Add pr_err() statements indicating the
fail and also the error value.

Signed-off-by: Nihar Chaithanya <niharchaithanya@gmail.com>
Link: https://lore.kernel.org/r/20241230185633.175690-6-niharchaithanya@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>