dt-bindings: coresight: Change CPU phandle to required property

Do not assume the affinity to CPU0 if cpu phandle is omitted.
Update the DT binding rules to reflect the same by changing it
to a required property.
Signed-off-by: NSai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Reviewed-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/0f7f4105d5ffea6ca4313271f3b3fee69da2106a.1562229018.git.saiprakash.ranjan@codeaurora.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt

@@ -26,8 +26,8 @@ Required properties:
 		processor core is clocked by the internal CPU clock, so it
 		is enabled with CPU clock by default.
 
-- cpu : the CPU phandle the debug module is affined to. When omitted
-	the module is considered to belong to CPU0.
+- cpu : the CPU phandle the debug module is affined to. Do not assume it
+        to default to CPU0 if omitted.
 
 Optional properties:
 

Documentation/devicetree/bindings/arm/coresight.txt

@@ -59,6 +59,11 @@ its hardware characteristcs.
 
 	* port or ports: see "Graph bindings for Coresight" below.
 
+* Additional required property for Embedded Trace Macrocell (version 3.x and
+  version 4.x):
+	* cpu: the cpu phandle this ETM/PTM is affined to. Do not
+	  assume it to default to CPU0 if omitted.
+
 * Additional required properties for System Trace Macrocells (STM):
 	* reg: along with the physical base address and length of the register
 	  set as described above, another entry is required to describe the
@@ -87,9 +92,6 @@ its hardware characteristcs.
 	* arm,cp14: must be present if the system accesses ETM/PTM management
 	  registers via co-processor 14.
 
-	* cpu: the cpu phandle this ETM/PTM is affined to. When omitted the
-	  source is considered to belong to CPU0.
-
 * Optional property for TMC:
 
 	* arm,buffer-size: size of contiguous buffer space for TMC ETR