maintainers: drop gmarull from device driver model

I won't be able to work on this area.

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

Author: gmarull

MAINTAINERS.yml

@@ -886,7 +886,6 @@ Demand Paging:
 Device Driver Model:
   status: maintained
   maintainers:
-    - gmarull
     - tbursztyka
   collaborators:
     - dcpleung