staging: gpib: pc2: Handle gpib_register_driver() errors

staging: gpib: pc2: Handle gpib_register_driver() errors

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

Unregister the previous gpib registering functions if subsequent
gpib_register_driver() fail and return the error value. Add pr_err()
statements indicating the fail and error value.

Signed-off-by: Nihar Chaithanya <niharchaithanya@gmail.com>
Link: https://lore.kernel.org/r/20241230185633.175690-15-niharchaithanya@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>