qcacmn: Enhance the qca_set_band enum value to BITMAP

Also introduce a new attribute QCA_WLAN_VENDOR_ATTR_SETBAND_MASK
to carry this new bitmask enum. This attribute shall consider the
bitmask combinations to define the respective Band combinations
and substitutes QCA_WLAN_VENDOR_ATTR_SETBAND_VALUE.

Change-Id: Ib00d93147e19593f24bd317c3962e6454e4eafc2
CRs-fixed: 2726283