staging: r8188eu: remove unused macros in sta_info.h

Some of the sta_* and STA_* macros are not used.
Remove those unused macros.

Signed-off-by: Abdun Nihaal <abdun.nihaal@gmail.com>
Link: https://lore.kernel.org/r/c2453078b2d46119d167f2d0e4690cc87fc4b77e.1644422181.git.abdun.nihaal@gmail.com


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