Bluetooth: btrtl: Firmware format v2 support

Realtek changed the format of the firmware file as v2. The driver
should implement the patch to extract the firmware data from the
firmware file. The future chips must apply this patch for firmware loading.
This patch is compatible with the both previous format and v2 as well.

Signed-off-by: Allen Chen <allen_chen@realsil.com.cn>
Signed-off-by: Alex Lu <alex_lu@realsil.com.cn>
Tested-by: Hilda Wu <hildawu@realtek.com>
Signed-off-by: Max Chou <max.chou@realtek.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>