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

In wilc_spi_read_size() remove the use of goto label '_fail_'. Changes
are 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>