Bluetooth: Annotate struct hci_drv_rp_read_info with __counted_by_le()

Add the __counted_by_le() compiler attribute to the flexible array
member 'supported_commands' to improve access bounds-checking via
CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>