MAINTAINERS: Fix the I3C entry

There's no include/dt-bindings/i3c/ directory, remove this F: entry
from the I3C file patterns.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joe Perches <joe@perches.com>
Reported-by: Joe Perches <joe@perches.com>
Fixes: 4f26d066 ("MAINTAINERS: Add myself as the I3C subsystem maintainer")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>