OvmfPkg/XenAcpiPlatformDxe: remove QEMU fw_cfg dependency

The QemuDetected() function wraps QemuFwCfgIsAvailable(); it always fails
on Xen. Because of that, we can eliminate the QemuDetected() call itself
from the Xen ACPI platform driver, and then the rest of "Qemu.c" becomes
useless -- the workhorse function of that source file is
QemuInstallAcpiTable(), which we no longer call.

Remove any dependencies that are no longer needed by the
XenAcpiPlatformDxe driver.

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien@xen.org>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2122
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20210526201446.12554-15-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

OvmfPkg/XenAcpiPlatformDxe/XenAcpiPlatformDxe.inf

@@ -25,23 +25,17 @@
   AcpiPlatform.c
   AcpiPlatform.h
   EntryPoint.c
-  Qemu.c
   Xen.c
 
 [Packages]
   MdeModulePkg/MdeModulePkg.dec
   MdePkg/MdePkg.dec
   OvmfPkg/OvmfPkg.dec
-  UefiCpuPkg/UefiCpuPkg.dec
 
 [LibraryClasses]
   BaseLib
-  BaseMemoryLib
   DebugLib
-  DxeServicesTableLib
-  MemoryAllocationLib
   PcdLib
-  QemuFwCfgLib
   UefiBootServicesTableLib
   UefiDriverEntryPoint
   XenPlatformLib
@@ -56,9 +50,6 @@
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiTableStorageFile
   gEfiMdeModulePkgTokenSpaceGuid.PcdPciDisableBusEnumeration
-  gUefiCpuPkgTokenSpaceGuid.PcdCpuLocalApicBaseAddress
-  gUefiOvmfPkgTokenSpaceGuid.Pcd8259LegacyModeEdgeLevel
-  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFdBaseAddress
 
 [Depex]
   gEfiAcpiTableProtocolGuid