tests.cfg: Remove redundant config files for guest s3/s4

These 2 files (guest_s3.cfg and guest_s4.cfg) are out of
date and should not be in here.

Signed-off-by: Qingtang Zhou <qzhou@redhat.com>
tests.guest_suspend: Fix a spelling typo

Signed-off-by: Qingtang Zhou <qzhou@redhat.com>
shared.cfg: Ignore dmesg output when check s3/s4 status

Signed-off-by: Qingtang Zhou <qzhou@redhat.com>
tests.guest_suspend: Check SSDT when disabling S4

Changes from V1:
 * Disable RHEL.5.i386 guest for this test since there
   is no iasl package for this platform.
 * Update the cmd for RHEL/Fedora guests separately.

Signed-off-by: Qingtang Zhou <qzhou@redhat.com>