Add a missing initialization of gd->env_valid in env_ext4_load
as it is already done in some other env device.
Set gd->env_valid = ENV_VALID in env_ext4_save() and env_ext4_load().
This patch allows to have a correct information in 'env info' command.
Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>