PM / Hibernate: Replace unintuitive 'if' condition in kernel/power/user.c with 'else'

In the snapshot_ioctl() function, under SNAPSHOT_FREEZE, the code below
freeze_processes() is a bit unintuitive. Improve it by replacing the
second 'if' condition with an 'else' clause.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>