Platform/Sgi: Add SMBIOS Type3 Table

Add the SMBIOS type 3 table (System Enclosure) that includes information
about manufacturer, type, serial number and other information related to
system enclosure.

Signed-off-by: Pranav Madhu <pranav.madhu@arm.com>
Reviewed-by: Thomas Abraham <thomas.abraham@arm.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>