staging: wlan-ng: fix expression continuation in prism2fw.c

checkpatch reports "CHECK: Logical continuations should be on the
previous line" when a continuation line begins with an
operator. Reformat the code so that the operator appears at the end of
the line being continued.

Signed-off-by: Tim Collier <osdevtc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>