Freezer: Fix APM emulation breakage

The APM emulation is currently broken as a result of commit
83144186
"Freezer: make kernel threads nonfreezable by default"
that removed the PF_NOFREEZE annotations from apm_ioctl() without
adding the appropriate freezer hooks.  Fix it and remove the
unnecessary variable flags from apm_ioctl().

This problem has been fixed in the mainline by
commit cb43c54c
"Freezer: Fix APM emulation breakage".

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>