staging: rtl8192u: Delete unnecesary braces in ieee80211/dot11d.c

Delete unnecesary braces and fix coding style these lines when It is
necessary in ieee80211/dot11d.c

Fix checkpatch.pl errors:
WARNING: braces {} are not necessary for single statement blocks
Signed-off-by: Ana Rey <anarey@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>