hccontrol: Support generic Bluetooth LE AdvData

hccontrol LE_Set_Advertising_Data does not currently allow construction
of manufacturer-specific type 0xFF AdvData. Fixed by a new data-entry
option -b "b1,b2,b3,...,bn" where b's are 8-bit byte strings (octets).

Signed-off-by: F. Duncanh <fduncanh@gmail.com>
Reviewed by: takawata, pouria
Pull Request: https://github.com/freebsd/freebsd-src/pull/2082