riscv: sifive: Add SiFive alternative ports

Add required ports of the Alternative scheme for SiFive.

Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
diff --git a/arch/riscv/Kconfig.erratas b/arch/riscv/Kconfig.erratas
index 4d0bafc..302e746 100644
--- a/arch/riscv/Kconfig.erratas
+++ b/arch/riscv/Kconfig.erratas
@@ -9,4 +9,14 @@
 	  code patching is performed once in the boot stages. It means
 	  that the overhead from this mechanism is just taken once.
 
+config ERRATA_SIFIVE
+	bool "SiFive errata"
+	depends on RISCV_ERRATA_ALTERNATIVE
+	help
+	  All SiFive errata Kconfig depend on this Kconfig. Disabling
+	  this Kconfig will disable all SiFive errata. Please say "Y"
+	  here if your platform uses SiFive CPU cores.
+
+	  Otherwise, please say "N" here to avoid unnecessary overhead.
+
 endmenu