wifi: rtw89: fw: add version field to BB MCU firmware element

8922AE has more than one hardware version, and they use different BB MCU
firmware, so occupy a byte from element priv[] to annotate version. Since
there are more than one firmware and only matched version is adopted,
return 1 to ignore not matched firmware.

     +===========================================+
     |  elm ID  | elm size | version  |          |
     +----------+----------+----------+----------+
     |                     |  element_priv[]     |
     +-------------------------------------------+

                change to  |
                           v

     +===========================================+
     |  elm ID  | elm size | version  |          |
     +----------+----------+----------+----------+
     |                     | cv | element_rsvd[] |
     +-------------------------------------------+

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20231213005054.10568-3-pkshih@realtek.com