configs: reset: fu540: enable dm reset framework for SiFive

Add necessary defconfig and Kconfig entries to enable SiFive SoC's
reset driver so as to utilise U-Boot's reset framework.

Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
Reviewed-by: Pragnesh Patel <Pragnesh.patel@sifive.com>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Tested-by: Bin Meng <bin.meng@windriver.com>
diff --git a/configs/sifive_fu540_defconfig b/configs/sifive_fu540_defconfig
index 5980406..070ef66 100644
--- a/configs/sifive_fu540_defconfig
+++ b/configs/sifive_fu540_defconfig
@@ -25,3 +25,5 @@
 CONFIG_SPL_DM_SEQ_ALIAS=y
 CONFIG_SPL_CLK=y
 CONFIG_DM_MTD=y
+CONFIG_SPL_DM_RESET=y
+CONFIG_DM_RESET=y