OvmfPkg: exclude Csm16.inf / Csm16.bin

The Csm16 module wraps the CONFIG_CSM build of SeaBIOS. "Csm16.inf" has
FILE_GUID 1547B4F3-3E8A-4FEF-81C8-328ED647AB1A, which was previously
referenced by the (now removed) CsmSupportLib, under the name
SYSTEM_ROM_FILE_GUID.

Nothing relies on the SeaBIOS binary any longer, so exclude the Csm16
module from all OVMF platforms.

(Note that the "OvmfPkg/Bhyve/Csm/BhyveCsm16/BhyveCsm16.inf" pathname that
the BhyveX64 platform refers to is bogus anyway.)

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Corvin Köhne <corvink@freebsd.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Rebecca Cran <rebecca@bsdio.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=4588
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20231110235820.644381-29-lersek@redhat.com>
Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Corvin Köhne <corvink@FreeBSD.org>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>

OvmfPkg/OvmfXen.dsc

@@ -694,10 +694,6 @@
   MdeModulePkg/Bus/Usb/UsbKbDxe/UsbKbDxe.inf
   MdeModulePkg/Bus/Usb/UsbMassStorageDxe/UsbMassStorageDxe.inf
 
-!ifdef $(CSM_ENABLE)
-  OvmfPkg/Csm/Csm16/Csm16.inf
-!endif
-
 !if $(TOOL_CHAIN_TAG) != "XCODE5"
   ShellPkg/DynamicCommand/TftpDynamicCommand/TftpDynamicCommand.inf {
     <PcdsFixedAtBuild>