staging: wilc1000: Fix some double unlock bugs in wilc_wlan_cleanup()

If ->hif_read_reg() or ->hif_write_reg() fail then the code unlocks
and keeps executing.  It should just return.

Fixes: c5c77ba1

 ("staging: wilc1000: Add SDIO/SPI 802.11 driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>