staging: wilc1000: remove the use of goto label in spi_cmd_complete()

In spi_cmd_complete() remove the use of goto label '_error_'. Changes
were done to avoid the use of '_' in label name.

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>