uwb: hwa-rc: fix memory leak at probe

hwarc_probe() allocates memory for hwarc, but does not free it
if uwb_rc_add() or hwarc_get_version() fail.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@ispras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>