x86: fsp: Add FSP_GRAPHICS_INFO_HOB

This adds a new HOB type for graphics information introduced in FSP
spec 1.1. When graphics capability is included in FSP and enabled,
FSP produces an FSP_GRAPHICS_INFO_HOB as described in the EFI PI
specification which provides information about the graphics mode and
framebuffer.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>