staging: rtl8723bs: fix tx power tables size

fix sizes of tx power tables to the real used
values (i.e. 2 bandwidth, 3 rate sections).

Delete MAX_BASE_NUM_IN_PHY_REG_PG_2_4 macro in
this process, for it expands to a larger than
needed rate section index value.

Modify comments accordingly.

Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/5f52295a8b17f68ad80ffb7b6301da83bfc11a68.1628329348.git.fabioaiuto83@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>