mwl8787: implement set/del peer

Since the marvell firmware takes the ratesset as a u32, we
might as well do the translation on the host.

We can also use the actual firmware rateids for the
ieee80211 rateset hw_values.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
mwl8787: print out device caps on firmware load

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>