staging: rtl8192u: r8192U_core: fix unecessary braces code style issue

braces {} are not necessary for any arm of a statement containing
one statement on each side.

Signed-off-by: Raphaël Beamonte <raphael.beamonte@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>