staging: rtl8192e: Remove unchanged variable frame_sync_monitor

Remove unchanged variable frame_sync_monitor and equations that have
always the same result to shorten code.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/0c4bdca5f5dbb93bb05c6b7f32136d4dfb3b0e4b.1681627603.git.philipp.g.hortmann@gmail.com


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