staging: brcm80211: remove ht_cap field from brcms_c_info structure

The field ht_cap was typed ieee80211_ht_cap from ieee80211.h. This
contained little endian annotated field cap_info resulting in sparse
endian warnings. It turned out the driver was setting the field, but
it was actually never used. Therefore it has been removed.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>