A few models offer the chance to set whether to resume from S3 and/or S4
when opening the lid.

[malattia@linux.it: create three sysfs files for S3/4/5 rather than
using a single one accepting a bitmask. Support S5 since the DSDT
exports it. Use a struct to hold all the related values, caching of the
current status value rather than re-reading all the time in the sysfs
show function.]
Signed-off-by: Marco Chiappero <marco@absence.it>
Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Matthew Garrett <mjg@redhat.com>