arm: apple: Disable SMBIOS again

Apple machines do not have memory below 4G.  Since U-Boot does
not support the SMBIOS 3 header structures this means we can't
support SMBIOS on these machines.  Unfortunately the refactoring
of the SMBIOS code this cycle accidentally enabled it again.

Fixes: 53fab13a ("efi: Use the installed SMBIOS tables")
Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>