Bluetooth: Add LE Features test macro

Added HCI macros to check LE Features. Also, added test
macros for 2M and Coded PHY support in HCI Controller.

Earlier a common test macro was used between BR/EDR and LE,
but since LE features do not use pages for feature, an
explicit macro for testing LE feature is added now.

Also, features field in LE device structure is now a single
dimension array of 8 octets.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>