cmd: env: add option for quiet output on env info

The "env info" can be use for test with -d and -p parameter,
in scripting case the output of the command is not needed.

This patch allows to deactivate this output with a new option "-q".

For example, we can save the environment if default
environment is used and persistent storage is managed with:
  if env info -p -d -q; then env save; fi

Without the quiet option, I have the unnecessary traces
First boot:
      Default environment is used
      Environment can be persisted
      Saving Environment to EXT4... File System is consistent

Next boot:
      Environment was loaded from persistent storage
      Environment can be persisted

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>