soc/sifive/fu540/memlayout.ld: Enlarge OpenSBI region

OpenSBI got bigger and doesn't fit anymore in 128K which causes coreboot
to not compiler anymore because the region overlaps with ramstage

This patch simply increases the size and uses the OpenSBI linker macro
instead.

Signed-off-by: Maximilian Brune <maximilian.brune@9elements.com>
Change-Id: If1ccaafbf91dae986c470020faf9c0b4fba448e5
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83046
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/soc/sifive/fu540/memlayout.ld b/src/soc/sifive/fu540/memlayout.ld
index 8fc875d..50af4f4 100644
--- a/src/soc/sifive/fu540/memlayout.ld
+++ b/src/soc/sifive/fu540/memlayout.ld
@@ -21,8 +21,8 @@
 	L2LIM_END(FU540_L2LIM + 2M)
 
 	DRAM_START(FU540_DRAM)
-	REGION(opensbi, FU540_DRAM, 128K, 4K)
-	RAMSTAGE(FU540_DRAM + 128K, 2M)
-	MEM_STACK(FU540_DRAM + 128K + 2M, 20K)
+	OPENSBI(FU540_DRAM, 256K)
+	RAMSTAGE(FU540_DRAM + 256K, 2M)
+	MEM_STACK(FU540_DRAM + 256K + 2M, 20K)
 	POSTRAM_CBFS_CACHE(FU540_DRAM + 3M, 29M)
 }