This patch introduce a flag property for the wpan phy structure.
The current flag settings in ieee802154_hw are accessable in mac802154
layer only which is okay for flags which indicates MAC handling which
are done by phy. For real PHY layer settings like cca mode, transmit
power, cca energy detection level.

The difference between these flags are that the MAC handling flags are
only handled in mac802154/HardMac layer e.g. on an interface up. The phy
settings are direct netlink calls from nl802154 into the driver layer
and the nl802154 need to have a chance to check if the driver supports
this handling before sending to the next layer.

We also check now on PHY flags while dumping and setting pib attributes.
In comparing with MIB attributes the 802.15.4 gives us an default value
which we assume when a transceiver implement less functionality. In case
of MIB settings the nl802154 layer doesn't need to check on the
ieee802154_hw flags then.
Signed-off-by: NAlexander Aring <alex.aring@gmail.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>