dt-bindings: Use Shawn Guo's preferred e-mail for i.MX bindings

Use Shawn Guo's kernel.org address for the i.MX related bindings
as per the MAINTAINERS entries.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20200818111245.17047-1-festevam@gmail.com


Signed-off-by: Rob Herring <robh@kernel.org>