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>