dt-bindings: net: ti,cc1352p7: Add bootloader-backdoor-gpios

bootloader-backdoor-gpio (along with reset-gpio) is used to enable
bootloader backdoor for flashing new firmware.

The pin and pin level to enable bootloader backdoor is configured using
the following CCFG variables in cc1352p7:
- SET_CCFG_BL_CONFIG_BL_PIN_NO
- SET_CCFG_BL_CONFIG_BL_LEVEL

Acked-by: Conor Dooley <[e-mail]>
Acked-by: Rob Herring (Arm) <[e-mail]>
Signed-off-by: Ayush Singh <[e-mail]>
Reviewed-by: Dhruva Gole <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/net/ti,cc1352p7.yaml

···
   reset-gpios:
     maxItems: 1
 
+  bootloader-backdoor-gpios:
+    maxItems: 1
+    description: |
+      gpios to enable bootloader backdoor in cc1352p7 bootloader to allow
+      flashing new firmware.
+
   vdds-supply: true
 
 required:
···
         clocks = <&sclk_hf 0>, <&sclk_lf 25>;
         clock-names = "sclk_hf", "sclk_lf";
         reset-gpios = <&pio 35 GPIO_ACTIVE_LOW>;
+        bootloader-backdoor-gpios = <&pio 36 GPIO_ACTIVE_LOW>;
         vdds-supply = <&vdds>;
       };
     };