dts: stm32 spi can configure the frame-format

If supported by the SPI instance and soc, this property will
configure the frame-format to be compliant with the TI mode.
By default, if supported, the frame-format is Motorola mode.

Signed-off-by: Francois Ramu <francois.ramu@st.com>

dts/bindings/spi/st,stm32-spi-common.yaml

@@ -12,6 +12,16 @@ properties:
     interrupts:
       required: true
 
+    frame-format:
+      type: boolean
+      required: false
+      description: |
+        Use Frame Format to support TI or motorola SPI mode when the SPI
+        interface is compatible with the TI protocol. The FRF bit of the
+        SPIx_CR2 configures the SPI to be compliant with this protocol.
+        false: SPI Motorola mode (default)
+        true: SPI TI mode
+
     pinctrl-0:
       type: phandles
       required: false