arm/dt: msm8974: Disable simulation UARTs by default

Disable the simulation UARTs in the top-level DTSI file and
explicitly enable them in the simulation DTS files to avoid
the maintenance burden of disabling them on all new
targets.

Change-Id: Ifc85b131c13abbf13ebe6066388e2c64efea0a51
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
diff --git a/arch/arm/boot/dts/msm8974-sim.dts b/arch/arm/boot/dts/msm8974-sim.dts
index 885453c..8cd925e 100644
--- a/arch/arm/boot/dts/msm8974-sim.dts
+++ b/arch/arm/boot/dts/msm8974-sim.dts
@@ -25,4 +25,12 @@
 			status = "ok";
 		};
 	};
+
+	serial@f991f000 {
+		status = "ok";
+	};
+
+	serial@f995e000 {
+		status = "ok";
+	};
 };