staging: wilc1000: use enum contants for mac status & added 'WILC_' prefix

Clubbed mac status constants inside the enum constant and also added
'WILC_' prefix to have better namespace.

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