mwifiex: save and copy AP's VHT capability info correctly

commit d51246481c7f28bbfa1f814ded2da65e531cd4b2 upstream.

While preparing association request, intersection of device's
VHT capability information and corresponding field advertised
by AP is used.

This patch fixes a couple errors while saving and copying vht_cap
and vht_oper fields from AP's beacon.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>