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>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index bfe6c16..e2b0a4f 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -601,6 +601,7 @@
 	  This command can be optionally used for evaluation in scripts:
 	  [-d] : evaluate whether default environment is used
 	  [-p] : evaluate whether environment can be persisted
+	  [-q] : quiet output
 	  The result of multiple evaluations will be combined with AND.
 
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