dt-bindings: net: qcom,ipa: support skipping GSI firmware load

Add a new enumerated value to those defined for the qcom,gsi-loader
property.  If the qcom,gsi-loader is "skip", the GSI firmware will
already be loaded, so neither the AP nor modem is required to load
GSI firmware.
Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/qcom,ipa.yaml

@@ -128,10 +128,12 @@ properties:
     enum:
       - self
       - modem
+      - skip
     description:
       Indicates how GSI firmware should be loaded.  If the AP loads
       and validates GSI firmware, this property has value "self".
       If the modem does this, this property has value "modem".
+      Otherwise, "skip" means GSI firmware loading is not required.
 
   modem-init:
     deprecated: true