IntelFrameworkModulePkg/GenericBdsLib: remove AcpiS3->S3Save() call

IntelFrameworkModulePkg/GenericBdsLib: remove AcpiS3->S3Save() call

The AcpiS3->S3Save() call needs to occur before the end-of-DXE event
is signalled. The end-of-DXE event needs to be signalled prior to
invoking any UEFI drivers, applications, or connecting consoles.

This means the call to S3Save() that occurs in BdsLibBootViaBootOption()
violates the ordering constraints, and should be removed. Since it is
the responsibility of the platform BDS to signal the end-of-DXE event,
it should also perform the AcpiS3->S3Save() call at an appropriate time.

Commit message update from Laszlo Ersek <lersek@redhat.com>:

Following Jiewen Yao's idea in

 http://thread.gmane.org/gmane.comp.bios.tianocore.devel/16088/focus=16146

platforms that
(1) use this exact instance of GenericBdsLib, *and*
(2) support S3

should now collect the S3 state
(3) in an End-of-Dxe callback in their AcpiS3SaveDxe drivers, *or*
(4) with an explicit AcpiS3->S3Save() call made to their AcpiS3SaveDxe
    drivers from their PlatformBdsLib instances.

OvmfPkg, which uses this GenericBdsLib instance, and has its own
AcpiS3SaveDxe fork, follows (3).

Vlv2TbltDevicePkg, which has a GenericBdsLib fork, and uses
IntelFrameworkModulePkg/Universal/Acpi/AcpiS3SaveDxe, follows (4).

There are no other platforms in the public edk2 repository that support
S3.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiewen Yao <Jiewen.Yao@intel.com>
[lersek@redhat.com: updated commit message]
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jeff Fan <jeff.fan@intel.com>
Cc: Jiewen Yao <Jiewen.Yao@intel.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18036 6f19259b-4bc3-4df7-8a09-765794883524