staging: wilc1000: fixes unnecessary variable replacement

This patch removes an unnecessary variable use for the errors and
returns errors directly without a result variable.

Signed-off-by: Leo Kim <leo.kim@atmel.com>
Signed-off-by: Tony Cho <tony.cho@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>