The file descriptor for /sys/power/state was never closed.  Reported
by Coverity.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>