cmd: env: add env load command

Add the new command env load to load the environment from
the current location gd->env_load_prio.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index bea2ddf..498fd31 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -604,6 +604,12 @@
 	  [-q] : quiet output
 	  The result of multiple evaluations will be combined with AND.
 
+config CMD_NVEDIT_LOAD
+	bool "env load"
+	help
+	  Load all environment variables from the compiled-in persistent
+	  storage.
+
 endmenu
 
 menu "Memory commands"