staging: lustre: Remove braces for single statement in kernel_user_comm.c

This patch fixed "WARNING: braces {} are not necessary for
single statement blocks" found by checkpatch.pl in
kernel_user_comm.c

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>