Since firmware header contains multiple secure sections, we need to trim
ignored sections, and then download firmware header with single one secure
section.

For secure boot, when downloading secure section, copy security key data
from MSS poll by key_idx read from efuse. If non-secure boot, no need this
extra copy.

           +---------------------------+ -\
           |      firmware header      |  |
           |                           |  |
           | +-----------------------+ |  | only preserve single one secure
           | | section type/size * N | |  | section
           | | ...                   | |  |
           | +-----------------------+ |  |
           +---------------------------+ -/
           :                           :
           +---------------------------+ -\
           | secure section type (ID:9)|  |
           |                           |  |
      +----|-> [ security key data ]   |  |
      |    +---------------------------+ -/
      |    |MSS Pool for above section |
      |    |  [ security key data 0 ]  |
      +----|- [ security key data 1 ]  |
by key_idx |  [ security key data 2 ]  |
           |  ...                      |
           +---------------------------+
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240204012627.9647-5-pkshih@realtek.com