cmd: sbi: add Supervisor Software Events extension

OpenSBI has implemented the Supervisor Software Events Extension.
Allow detecting it in the sbi command.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/cmd/riscv/sbi.c b/cmd/riscv/sbi.c
index bd9d9c4..55507b0 100644
--- a/cmd/riscv/sbi.c
+++ b/cmd/riscv/sbi.c
@@ -54,6 +54,7 @@
 	{ SBI_EXT_NACL,			      "Nested Acceleration Extension" },
 	{ SBI_EXT_STA,			      "Steal-time Accounting Extension" },
 	{ SBI_EXT_DBTR,			      "Debug Trigger Extension" },
+	{ SBI_EXT_SSE,			      "Supervisor Software Events" },
 };
 
 static int do_sbi(struct cmd_tbl *cmdtp, int flag, int argc,