wifi: rtw88: Don't use static local variable in rtw8822b_set_tx_power_index_by_rate

wifi: rtw88: Don't use static local variable in rtw8822b_set_tx_power_index_by_rate

[ Upstream commit 00451eb3bec763f708e7e58326468c1e575e5a66 ]

Some users want to plug two identical USB devices at the same time.
This static variable could theoretically cause them to use incorrect
TX power values.

Move the variable to the caller and pass a pointer to it to
rtw8822b_set_tx_power_index_by_rate().

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/8a60f581-0ab5-4d98-a97d-dd83b605008f@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>