doc: fix devicetree lexer warnings

Some warnings for invalid DT syntax have been fixed.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

doc/guides/dts/bindings.rst

@@ -687,7 +687,7 @@ either an SPI or an I2C controller, like this:
 
 .. code-block:: devicetree
 
-   spi-bus@... {
+   spi-bus@0 {
       /* ... some compatible with 'bus: spi', etc. ... */
 
       sensor@0 {
@@ -697,7 +697,7 @@ either an SPI or an I2C controller, like this:
       };
    };
 
-   i2c-bus@... {
+   i2c-bus@0 {
       /* ... some compatible with 'bus: i2c', etc. ... */
 
       sensor@79 {
@@ -751,12 +751,12 @@ looked up in each of the PWM controller nodes ``pwm0`` and ``pwm3``, like so:
 
 .. code-block:: devicetree
 
-   pwm0: pwm@... {
+   pwm0: pwm@0 {
    	compatible = "foo,pwm";
    	#pwm-cells = <2>;
    };
 
-   pwm3: pwm@... {
+   pwm3: pwm@3 {
    	compatible = "bar,pwm";
    	#pwm-cells = <1>;
    };

doc/guides/dts/howtos.rst

@@ -508,10 +508,10 @@ this:
 
    / {
            soc {
-                   mydevice0: dev@... {
+                   mydevice0: dev@0 {
                            compatible = "vnd,my-device";
                    };
-                   mydevice1: dev@... {
+                   mydevice1: dev@1 {
                            compatible = "vnd,my-device";
                    };
            };
@@ -659,7 +659,7 @@ node with path ``/soc/i2c@12340000`` in a C/C++ file:
 
 And if you're trying to **set** that property in a devicetree overlay:
 
-.. code-block:: devicetree
+.. code-block:: none
 
    /*
     * foo.overlay: DTS names with special characters, etc.

samples/basic/button/README.rst

@@ -48,7 +48,7 @@ simplicity.
    	};
 
    	soc {
-   		gpio0: gpio@... {
+   		gpio0: gpio@0 {
    			status = "okay";
    			gpio-controller;
    			#gpio-cells = <2>;