MAINTAINERS: replace free-electrons.com by bootlin.com for Thomas Petazzoni

Free Electrons is now called Bootlin, and my e-mail address was
changed as well, so this commit updates the entries in the MAINTAINERS
file accordingly.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>