mips: mtmips: Increase CONFIG_SPL_SYS_MALLOC_F_LEN

Since SPL now uses malloc to allocate the buffer for the compressed
image before decompression to the destination address, we need to
configure a big enough malloc space in SPL. 256k seems to be big
enough even for the GARDENA board.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/configs/linkit-smart-7688_defconfig b/configs/linkit-smart-7688_defconfig
index 629c33a..8ec6693 100644
--- a/configs/linkit-smart-7688_defconfig
+++ b/configs/linkit-smart-7688_defconfig
@@ -5,7 +5,7 @@
 CONFIG_ENV_OFFSET=0x80000
 CONFIG_ENV_SECT_SIZE=0x10000
 CONFIG_SPL_SERIAL_SUPPORT=y
-CONFIG_SPL_SYS_MALLOC_F_LEN=0x20000
+CONFIG_SPL_SYS_MALLOC_F_LEN=0x40000
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_SPL=y
 CONFIG_ARCH_MTMIPS=y