staging: gpib: agilent_82357a: Handle gpib_register_driver() errors

staging: gpib: agilent_82357a: Handle gpib_register_driver() errors

The usb_register() function can fail and returns an error value which
is not returned. The function gpib_register_driver() can also fail
which can result in semi-registered module.

In case gpib_register_driver() fails unregister the previous usb driver
registering function. Return the error value if gpib_register_driver()
or usb_register() functions fail. Add pr_err when registering driver
fails also indicating the error value.

Signed-off-by: Nihar Chaithanya <niharchaithanya@gmail.com>
Link: https://lore.kernel.org/r/20241230185633.175690-4-niharchaithanya@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>