dts: bindings: adc: Remove unused properties for STM32 ADC

Boolean properties for STM32 ADC internal channels are not used anymore
and can be removed. It is replaced by channel number properties.

Signed-off-by: Guillaume Gautier <guillaume.gautier-ext@st.com>
diff --git a/dts/bindings/adc/st,stm32-adc.yaml b/dts/bindings/adc/st,stm32-adc.yaml
index 8fe15c6..910f5f0 100644
--- a/dts/bindings/adc/st,stm32-adc.yaml
+++ b/dts/bindings/adc/st,stm32-adc.yaml
@@ -32,18 +32,6 @@
     default: 3300
     description: Indicates the reference voltage of the ADC in mV (on the target board).
 
-  has-temp-channel:
-    type: boolean
-    description: Indicates if the ADC has a dedicated internal temperature sensor channel.
-
-  has-vref-channel:
-    type: boolean
-    description: Indicates if the ADC has a dedicated internal voltage reference channel.
-
-  has-vbat-channel:
-    type: boolean
-    description: Indicates if the ADC has a dedicated internal vbat monitoring channel.
-
   temp-channel:
     type: int
     description: Indicates the ADC channel of the internal temperature sensor.