OvmfPkg/SmbiosPlatformDxe: declare InstallAllStructures() in header file

OvmfPkg/SmbiosPlatformDxe: declare InstallAllStructures() in header file

Add an extern declaration for the InstallAllStructures() function to the
"SmbiosPlatformDxe.h" header file. (The leading comment block and the
prototype are simply copied from "SmbiosPlatformDxe.c".)

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
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: <20210526201446.12554-41-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>