soc/mediatek/mt8196: Add 24MB framebuffer region

Add framebuffer region to reserve 24MB for the boot logo feature.

BUG=b:319511268
TEST=The logo is shown in the ramstage.

Change-Id: I183651f7bd28de5551a15bd335bc2eed5f0804eb
Signed-off-by: Yidi Lin <yidilin@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/89544
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>

src/soc/mediatek/mt8196/include/soc/memlayout.ld

@@ -73,4 +73,5 @@ SECTIONS
 	RESV_MEMORY_GPUEB(0xA0000000, 2M)
 	/* Reserved memory for the dedicated secured memory allocator of GPU Mali firmware */
 	GPU_SEC_BUF(0xA2000000, 16M)
+	FRAMEBUFFER(0xBEC00000, 24M)
 }