rtlwifi: rtl8192de: fix ofdm power compensation

ofdm_index[] is used to indicate how many power compensation is needed to
current thermal value. For internal PA module or 2.4G band, the min_index
is different from other cases.

This issue originally is reported by Dan. He found the size of ofdm_index[]
is 2, but access index 'i' may be equal to 2 if 'rf' is 2 in case of
'is2t'.

In fact, the chunk of code is added to wrong place, so move it back to
proper place, and then power compensation and buffer overflow are fixed.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201207031903.7599-1-pkshih@realtek.com