smbios: smbios.h should not import ofnode.h

The smbios.h include does not use any definitions from ofnode.h.
So don't include it.

As DECLARE_GLOBAL_DATA_PTR is no longer defined via dm/of.h we need to
add it to efi_smbios.c.

Add now missing includes to smbios-parser.c.

Remove a superfluous check comparing the sizes of the SMBIOS 2.1 and SMBIOS
3.0 anchors.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>