refactor(ethos-n): move build flags to ethosn_npu.mk

The build flags to enable the Arm(R) Ethos(TM)-N NPU driver are in arm
platform specific make files i.e. plat/arm/common/arm_common.mk. These
flags are renamed and moved to ethosn_npu.mk. Other source and make
files are changed to reflect the changes in these flags.

Signed-off-by: Rajasekaran Kalidoss <rajasekaran.kalidoss@arm.com>
Change-Id: I6fd20225343c574cb5ac1f0f32ff2fc28ef37ea6
diff --git a/fdts/juno.dts b/fdts/juno.dts
index 56fe167..8e373e7 100644
--- a/fdts/juno.dts
+++ b/fdts/juno.dts
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2023, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -10,6 +10,6 @@
 
 };
 
-#if ARM_ETHOSN_NPU_DRIVER
+#if ETHOSN_NPU_DRIVER
 	#include "juno-ethosn.dtsi"
 #endif