staging: rtl8192e: Remove ant_pwr_diff which is always zero

ant_pwr_diff is set to zero and then masked which will always result in
zero. Remove ant_pwr_diff and use zero direct as it is just useless
code.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/a550004dcdeb9e0b716f69033a541457c1f12c86.1674244819.git.philipp.g.hortmann@gmail.com


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