OvmfPkg/SmbiosPlatformDxe: split Xen entry point from QEMU entry point

OvmfPkg/SmbiosPlatformDxe: split Xen entry point from QEMU entry point

Remove the SmbiosTablePublishEntry() function from "SmbiosPlatformDxe.c".
"SmbiosPlatformDxe.c" becomes hypervisor-agnostic.

Add SmbiosTablePublishEntry() back, simplified for QEMU, to the existent
file "Qemu.c". The GetQemuSmbiosTables() function no longer needs to be
declared in "SmbiosPlatformDxe.h"; "SmbiosPlatformDxe.h" becomes
hypervisor-agnostic.

Add SmbiosTablePublishEntry() back, renamed and simplified for Xen, to the
new, arch-independent file "Xen.c". (The existent Xen-specific C files are
arch-dependent.)

Update both INF files; remove the dependencies that are now superfluous in
each.

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: <20210526201446.12554-43-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>