libpayload: Cache copy of cb_framebuffer struct

Our AArch64 code supports dynamic framebuffer allocation which
makes it necessary to change the framebuffer information during
runtime. Having a pointer inside `libsysinfo` made a mess of it
as the pointer would either refer to the original struct inside
the coreboot table or to a new struct inside payload space. The
latter would be unaffected by a relocation of the payload.

Instead of the pointer, we'll always keep a copy of the whole
struct, which can be altered on demand without affecting the
coreboot table. To align the `video/graphics` driver with the
console driver, we also replace `fbaddr` with a macro `FB` that
calls phys_to_virt().

Change-Id: I3edc09cdb502a71516c1ee71457c1f8dcd01c119
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43578
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>

payloads/libpayload/libc/coreboot.c

@@ -186,8 +186,7 @@ static void cb_parse_checksum(void *ptr, struct sysinfo_t *info)
 #if CONFIG(LP_COREBOOT_VIDEO_CONSOLE)
 static void cb_parse_framebuffer(void *ptr, struct sysinfo_t *info)
 {
-	/* ptr points to a coreboot table entry and is already virtual */
-	info->framebuffer = ptr;
+	info->framebuffer = *(struct cb_framebuffer *)ptr;
 }
 #endif