Bluetooth: Implement PHY changed event

This defines and implement phy changed event and send it to user
whenever selected PHYs changes using SET_PHY_CONFIGURATION.

This will be also trigerred when BREDR pkt_type is changed using
the legacy ioctl HCISETPTYPE.

@ MGMT Command: Set PHY Configuration (0x0045) plen 4
		Selected PHYs: 0x7fff
		  BR 1M 1SLOT
		  BR 1M 3SLOT
		  BR 1M 5SLOT
		  EDR 2M 1SLOT
		  EDR 2M 3SLOT
		  EDR 2M 5SLOT
		  EDR 3M 1SLOT
		  EDR 3M 3SLOT
		  EDR 3M 5SLOT
		  LE 1M TX
		  LE 1M RX
		  LE 2M TX
		  LE 2M RX
		  LE CODED TX
		  LE CODED RX
< HCI Command: LE Set Default PHY (0x08|0x0031) plen 3
		All PHYs preference: 0x00
		TX PHYs preference: 0x07
		  LE 1M
		  LE 2M
		  LE Coded
		RX PHYs preference: 0x07
		  LE 1M
		  LE 2M
		  LE Coded
> HCI Event: Command Complete (0x0e) plen 4
	  LE Set Default PHY (0x08|0x0031) ncmd 1
		Status: Success (0x00)
@ MGMT Event: Command Complete (0x0001) plen 3
	  Set PHY Configuration (0x0045) plen 0
		Status: Success (0x00)
@ MGMT Event: PHY Configuration Changed (0x0026) plen 4
		Selected PHYs: 0x7fff
		  BR 1M 1SLOT
		  BR 1M 3SLOT
		  BR 1M 5SLOT
		  EDR 2M 1SLOT
		  EDR 2M 3SLOT
		  EDR 2M 5SLOT
		  EDR 3M 1SLOT
		  EDR 3M 3SLOT
		  EDR 3M 5SLOT
		  LE 1M TX
		  LE 1M RX
		  LE 2M TX
		  LE 2M RX
		  LE CODED TX
		  LE CODED RX

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