MAINTAINERS: Remove myself from SAM Platform collaborators

I've been unable to participate properly for some time, apologies all.

Signed-off-by: Attie Grande <attie.grande@argentum-systems.co.uk>

Author: attie-argentum

MAINTAINERS.yml

@@ -4096,7 +4096,6 @@ Microchip SAM Platforms:
   maintainers:
     - nandojve
   collaborators:
-    - attie-argentum
     - pdgendt
     - mnkp
     - stephanosio