configs: sandbox: activate command env select and env load

Add support of environment location with the new env command:
'env select' and 'env load'

The ENV backend is selected by priority order
- 0 = "nowhere" (default at boot)
- 1 = "EXT4"

To test EXT4 env support, this backend is selected by name:
> env select EXT4

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

configs/sandbox64_defconfig

@@ -31,6 +31,8 @@ CONFIG_CMD_ENV_CALLBACK=y
 CONFIG_CMD_ENV_FLAGS=y
 CONFIG_CMD_NVEDIT_EFI=y
 CONFIG_CMD_NVEDIT_INFO=y
+CONFIG_CMD_NVEDIT_LOAD=y
+CONFIG_CMD_NVEDIT_SELECT=y
 CONFIG_LOOPW=y
 CONFIG_CMD_MD5SUM=y
 CONFIG_CMD_MEMINFO=y

configs/sandbox_defconfig

@@ -36,6 +36,8 @@ CONFIG_CMD_ENV_CALLBACK=y
 CONFIG_CMD_ENV_FLAGS=y
 CONFIG_CMD_NVEDIT_EFI=y
 CONFIG_CMD_NVEDIT_INFO=y
+CONFIG_CMD_NVEDIT_LOAD=y
+CONFIG_CMD_NVEDIT_SELECT=y
 CONFIG_LOOPW=y
 CONFIG_CMD_MD5SUM=y
 CONFIG_CMD_MEMINFO=y

configs/sandbox_flattree_defconfig

@@ -25,6 +25,8 @@ CONFIG_CMD_BOOTEFI_HELLO=y
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_GREPENV=y
 CONFIG_CMD_NVEDIT_INFO=y
+CONFIG_CMD_NVEDIT_LOAD=y
+CONFIG_CMD_NVEDIT_SELECT=y
 CONFIG_LOOPW=y
 CONFIG_CMD_MD5SUM=y
 CONFIG_CMD_MEMINFO=y

configs/sandbox_spl_defconfig

@@ -37,6 +37,8 @@ CONFIG_CMD_GREPENV=y
 CONFIG_CMD_ENV_CALLBACK=y
 CONFIG_CMD_ENV_FLAGS=y
 CONFIG_CMD_NVEDIT_INFO=y
+CONFIG_CMD_NVEDIT_LOAD=y
+CONFIG_CMD_NVEDIT_SELECT=y
 CONFIG_LOOPW=y
 CONFIG_CMD_MD5SUM=y
 CONFIG_CMD_MEMINFO=y