lib/coreboot_table: Show splashscreen in lb_table_init

Every vga init implementation needs to cache the framebuffer state
to be able to fill the lb_framebuffer struct later on in the
fill_lb_framebuffer call. Showing the bootsplash afterwards
guarantees to have the same interface into all the vga drivers.

This is by far from ideal, as it only allows for a single driver at
compile-time and should be adapted in the future.

It was tested on the wip razer blade stealth using vgabios @ 1280x1024
and also in Qemu @ 1280x1024.
By default the qemu framebuffer will be initialized in 800x600@32.
This can be overwriten by configuration by setting
CONFIG_DRIVERS_EMULATION_QEMU_BOCHS_{X,Y}RES .

Change-Id: I4bec06d22423627e8f429c4b47e0dc9920f1464e
Signed-off-by: Johanna Schander <coreboot@mimoja.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34599
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/include/bootsplash.h

@@ -18,12 +18,6 @@
 
 #include <types.h>
 
-/**
- * Wraps bootsplash setup for vesa
- */
-void set_vesa_bootsplash(void);
-
-
 /**
  * Sets up the framebuffer with the bootsplash.jpg from cbfs.
  * Returns 0 on success