mips: spl: configure SYS_MALLOC_F_LEN independently for SPL and full U-Boot

Some platforms have very limited SRAM to run SPL code, so there may
not be the same amount space for a malloc pool before relocation in
the SPL stage as the normal U-Boot stage.

Make SPL and (the full) U-Boot stage use independent SYS_MALLOC_F_LEN,
so the size of pre-relocation malloc pool can be configured memory
space independently.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Acked-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
[fixed up commit-message:]
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S
index 952c57a..42af9de 100644
--- a/arch/mips/cpu/start.S
+++ b/arch/mips/cpu/start.S
@@ -60,8 +60,8 @@
 		sp, sp, GD_SIZE		# reserve space for gd
 	and	sp, sp, t0		# force 16 byte alignment
 	move	k0, sp			# save gd pointer
-#ifdef CONFIG_SYS_MALLOC_F_LEN
-	li	t2, CONFIG_SYS_MALLOC_F_LEN
+#if CONFIG_VAL(SYS_MALLOC_F_LEN)
+	li	t2, CONFIG_VAL(SYS_MALLOC_F_LEN)
 	PTR_SUBU \
 		sp, sp, t2		# reserve space for early malloc
 	and	sp, sp, t0		# force 16 byte alignment
@@ -75,7 +75,7 @@
 	blt	t0, t1, 1b
 	 PTR_ADDIU t0, PTRSIZE
 
-#ifdef CONFIG_SYS_MALLOC_F_LEN
+#if CONFIG_VAL(SYS_MALLOC_F_LEN)
 	PTR_S	sp, GD_MALLOC_BASE(k0)	# gd->malloc_base offset
 #endif
 	.endm