riscv: mpfs-icicle-kit: Increase SYS_MALLOC_F_LEN

The RISC-V architecture default value of CONFIG_SYS_MALLOC_F_LEN
(0x1000) would not provide enough memory for devices like mpfs
clock and ns16550 serial to bind well before relocation.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Padmarao Begari <padmarao.begari@microchip.com>
Tested-by: Padmarao Begari <padmarao.begari@microchip.com>
diff --git a/configs/microchip_mpfs_icicle_defconfig b/configs/microchip_mpfs_icicle_defconfig
index 0c15c3b..1cb2920 100644
--- a/configs/microchip_mpfs_icicle_defconfig
+++ b/configs/microchip_mpfs_icicle_defconfig
@@ -1,4 +1,5 @@
 CONFIG_RISCV=y
+CONFIG_SYS_MALLOC_F_LEN=0x2000
 CONFIG_ENV_SIZE=0x2000
 CONFIG_DEFAULT_DEVICE_TREE="microchip-mpfs-icicle-kit"
 CONFIG_TARGET_MICROCHIP_ICICLE=y