drivers: Replace multiple fill_fb_framebuffer with single instance

Currently it's not possible to add multiple graphics driver into
one coreboot image. This patch series will fix this issue by providing
a single API that multiple graphics driver can use.

This is required for platforms that have two graphic cards, but
different graphic drivers, like Intel+Aspeed on server platforms or
Intel+Nvidia on consumer notebooks.

The goal is to remove duplicated fill_fb_framebuffer(), the advertisment
of multiple indepent framebuffers in coreboot tables, and better
runtime/build time graphic configuration options.

Replace all duplications of fill_fb_framebuffer and provide a single one
in edid_fill_fb.c. Should not change the current behaviour as still only
one graphic driver can be active at time.

Tested on:
* QEMU VGA cirrus
* QEMU VGA bochs
* Aspeed AST2500 NGI
* Lenovo X220 using libgfxinit
* Intel FSP2.0 GOP

Change-Id: Ife507f7e7beaf59854e533551b4b87ea6980c1f4
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
---
M src/device/oprom/realmode/x86.c
M src/device/oprom/yabel/vbe.c
M src/drivers/intel/fsp1_1/fsp_gop.c
M src/drivers/intel/fsp2_0/graphics.c
M src/drivers/intel/fsp2_0/include/fsp/util.h
M src/drivers/intel/gma/gma-gfx_init.ads
M src/drivers/intel/gma/hires_fb/gma-gfx_init.adb
M src/drivers/intel/gma/text_fb/gma-gfx_init.adb
M src/drivers/xgi/common/Kconfig
M src/drivers/xgi/common/xgi_coreboot.c
M src/lib/Kconfig
M src/lib/Makefile.inc
12 files changed, 144 insertions(+), 253 deletions(-)