Revert "PM / Hibernate: Reduce autotuned default image size"

This reverts commit bea3864fb627d110933cfb8babe048b63c4fc76e
(PM / Hibernate: Reduce autotuned default image size), because users
are now able to resolve the issue this commit was supposed to address
in a different way (i.e. by using the new /sys/power/reserved_size
interface).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>