[PATCH] libertas: revert CAPINFO_MASK to its original value

CAPINFO_MASK changed on commits 981f187b and a091095b. Reverting to the original
value.  Also move CAPINFO_MASK into the sole user, join.c.  CAPINFO_MASK
should be in host CPU byte order; capability is converted to device
byte order elsewhere.

This fixes OLPC ticket #2161

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