ALSA: riptide - proper handling of pci_register_driver for joystick
We need to check returning error for pci_register_driver(&joystick_driver)
On failure, we should unregister formerly registered audio drivers
This also fixed the compiler warning :
CC [M] sound/pci/riptide/riptide.o
sound/pci/riptide/riptide.c: In function ‘alsa_card_riptide_init’:
sound/pci/riptide/riptide.c:2200: warning: ignoring return value of ‘__pci_register_driver’, declared with attribute warn_unused_result