MAINTAINERS: Add the Lantiq PEF2256 driver entry

After contributing the driver, add myself as the maintainer for the
Lantiq PEF2256 driver.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/20231128132534.258459-6-herve.codina@bootlin.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>