staging: rtl8712: style fix unneeded else

This patch fixes a coding style issues in the rtl8712 module as noted
by checkpatch.pl where an unnecessary else is used.

It fixes the following checkpatch.pl warning:

WARNING: else is not generally useful after a break or return

Signed-off-by: Martin Homuth <martin@martinhomuth.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>