display: mayfly: Drop 90Hz timing

* Switching to 90Hz results in a very noticeable color shift, especially when displaying dark content.
  So remove it for a better visual experience.

Change-Id: Ic2115c357fd6b74da135f668be4f0279ba25de5e

qcom/display/display/mayfly-sde-display-mtp.dtsi

@@ -66,6 +66,7 @@
 
 			qcom,default-topology-index = <0>;
 		};
+		/delete-node/ timing@2;
 	};
 };