Remove the hardcoded ST logo no longer in use

The patch removes the hardcoded ST logo from the code, as it is no
longer used.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>