MAINTAINERS: include all of framer under pef2256

The "framer" infrastructure only has one driver - pef2256
and is not covered by any MAINTAINERS entry of its own.
This leads to author not being CCed on patches.
Let's include all of framer/ under the pef2256 entry.
We can split it in the very unlikely event of another
driver appearing.

Link: https://lore.kernel.org/aZefB5f3EAkQQM1m@google.com
Acked-by: Herve Codina <herve.codina@bootlin.com>
Link: https://patch.msgid.link/20260221011858.3403605-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>