Revert "rtl8187: fix tx power reading"

This reverts commit e4128a54d790658ab265c915e5da9153ff74af97.

On Sunday 02 December 2007 17:17:51 Michael Wu wrote:
> CCK and OFDM power levels are stored in adjacent bytes, not nibbles.
>
This turns out to be true only for rtl8180. On rtl8187, power levels are
indeed stored in nibbles, so this patch is wrong. Please revert this patch.

Signed-off-by: John W. Linville <linville@tuxdriver.com>