env: ext4: add support of command env erase

Add support of opts erase for env in ext4,
this opts is used by command 'env erase'.

This command only fill the env file (CONFIG_ENV_EXT4_FILE)
with 0, the CRC and the saved environment becomes invalid.

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