dt-bindings: leds: Drop redundant cpus enum match

Commit e91a4d5d ("dt-bindings: leds: Document commonly used
LED triggers") introduced a enum match for cpu, while a pattern
'^cpu[0-9]*$' already exists.

This causes linux,default-trigger = "cpu" to have more than one match
and generates the following dtbs_check warning:

arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dtb: leds: led-2:linux,default-trigger: More than one condition true in oneOf schema:
	{'$ref': '/schemas/types.yaml#/definitions/string',
	 'oneOf': [{'items': [{'enum': ['backlight',
	                                'default-on',
	                                'heartbeat',
	                                'disk-activity',
	                                'disk-read',
	                                'disk-write',
	                                'timer',
	                                'pattern',
	                                'audio-micmute',
	                                'audio-mute',
	                                'bluetooth-power',
	                                'cpu',
	                                'flash',
	                                'kbd-capslock',
	                                'mtd',
	                                'nand-disk',
	                                'none',
	                                'torch',
	                                'usb-gadget',
	                                'usb-host',
	                                'usbport']}],
	            'maxItems': 1,
	            'minItems': 1,
	            'type': 'array'},
	           {'items': [{'pattern': '^cpu[0-9]*$'}],
	            'maxItems': 1,
	            'minItems': 1,
	            'type': 'array'},
	           {'items': [{'pattern': '^hci[0-9]+-power$'}],
	            'maxItems': 1,
	            'minItems': 1,
	            'type': 'array'},
	           {'items': [{'pattern': '^mmc[0-9]+$'}],
	            'maxItems': 1,
	            'minItems': 1,
	            'type': 'array'},
	           {'items': [{'pattern': '^phy[0-9]+tx$'}],
	            'maxItems': 1,
	            'minItems': 1,
	            'type': 'array'}]}

Drop the explicit match against cpu since the pattern match already
covers the same.

Fixes: e91a4d5d ("dt-bindings: leds: Document commonly used LED triggers")
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230424151437.256073-1-nm@ti.com

Documentation/devicetree/bindings/leds/common.yaml

@@ -105,8 +105,6 @@ properties:
           - audio-mute
             # LED indicates bluetooth power state
           - bluetooth-power
-            # LED indicates activity of all CPUs
-          - cpu
             # LED indicates camera flash state
           - flash
             # LED indicated keyboard capslock