rsi: Handle usb multi-byte write failure case properly

In function usb_write_register_multiple, if any intermediate block transfer
is failed, further operations should be terminated. 'else' is removed, as
there is no significance for it after return.

Signed-off-by: Prameela Rani Garnepudi <prameela.j04cs@gmail.com>
Signed-off-by: Amitkumar Karwar <amit.karwar@redpinesignals.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>