staging: rtl8723bs: use MAX_RF_PATH_NUM as ceiling to rf path index

staging: rtl8723bs: use MAX_RF_PATH_NUM as ceiling to rf path index

use MAX_RF_PATH_NUM as ceiling to rf path index.
Only 2 rf paths are used, not 4. Remove also
TX_POWER_BY_RATE_NUM_RF left unused.

Use RF_PATH_A as loop starting point instead of
hardcoded 0, as in other places.

Related comments modified accordingly.

Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/88da23cef57131b39a63b2757b91f959553dd65d.1628329348.git.fabioaiuto83@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>