x86: efi_loader: Ensure the SMBIOS tables are sent via EFI

x86: efi_loader: Ensure the SMBIOS tables are sent via EFI

The EFI-loader code has not been fully converted to use bloblist, so
relies on the SMBIOS-table address being set in global_data.

Set this up in write_tables() so that the SMBIOS tables are actually
available.

Enable the command for x86 QEMU so that the SMBIOS tests actually run.

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: 83ce35d6ebb ("emulation: Use bloblist to hold tables")
Reported-by: Niklas Sombert <niklas.sombert@uni-duesseldorf.de>
Tested-by: Niklas Sombert <niklas.sombert@uni-duesseldorf.de>
Tested-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>