patman: Detect unexpected END

patman: Detect unexpected END

Detect unexpected 'END' line when a section is not detected.

This patch detect issue when tag name for section start is misspelled,
for example 'Commit-note:' for 'Commit-notes:'

  Commit-note:
  ....
  END

Then 'Commit-note:' is removed silently by re_remove = "Commit-\w*:"
but 'END' is kept in commit message.

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