maintainers: set gmarull as pin control collaborator

I won't be able to actively maintain this subsystem, but maybe help
reviewing on my spare time. The API has not changed from its
introduction, it's been mostly new drivers.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

Author: gmarull

MAINTAINERS.yml

@@ -1932,8 +1932,8 @@ Release Notes:
     - samples.drivers.peci
 
 "Drivers: Pin Control":
-  status: maintained
-  maintainers:
+  status: odd fixes
+  collaborators:
     - gmarull
   files:
     - doc/hardware/pinctrl/