[PATCH] libertas: convert libertas_mpp into anycast_mask

With firmware 5.220.11.p5, this allows to specify the anycast addresses the
device will listen to.

The anycast address range is C0:27:C0:27:C0:XX where XX goes from 00 to 1F (or
0 to 31 in dec). The value to write on anycast_mask will specify which
addresses the device listens to. Bits in a 32 bit int are numbered from 0
(least significative bit) to 31. A specific address ending in YY will be
listened to if bit YY in the value is set to one.

Examples:

0x00000000 : do not listen to any anycast address
0xFFFFFFFF : listen to every anycast address from :00 to :1F
0x00000013 : listen to anycast addresses :00, :01 and :04

Signed-off-by: Luis Carlos Cobo <luisca@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>