Bluetooth: Define PHY flags in hdev and set 1M as default

1M is mandatory to be supported by LE controllers and the same
would be set in power on. This patch defines hdev flags for
LE PHYs and set 1M to default.

Signed-off-by: Jaganath Kanakkassery <jaganathx.kanakkassery@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>