wifi: rtw89: avoid reading out of bounds when loading TX power FW elements

Because the loop-expression will do one more time before getting false from
cond-expression, the original code copied one more entry size beyond valid
region.

Fix it by moving the entry copy to loop-body.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20240902015803.20420-1-pkshih@realtek.com