MAINTAINERS: Update some st.com email addresses to foss.st.com

Update some st.com to foss.st.com addresses related to STMicroelectronics
drivers. All these people will now use this new email address for upstream
activities.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Link: https://lore.kernel.org/r/20210216074929.29033-2-patrice.chotard@foss.st.com

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Signed-off-by: Arnd Bergmann <arnd@arndb.de>