Documentation: synopsys-dw-mshc: remove the unused properties

"support-highspeed" was the obsoleted property.
And "broken-cd" is not synopsys specific property.
It can be referred to mmc.txt binding Documentation.
Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>
Acked-by: NRob Herring <robh@kernel.org>
Reviewed-by: NShawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt

@@ -75,11 +75,6 @@ Optional properties:
 * card-detect-delay: Delay in milli-seconds before detecting card after card
   insert event. The default value is 0.
 
-* supports-highspeed (DEPRECATED): Enables support for high speed cards (up to 50MHz)
-			   (use "cap-mmc-highspeed" or "cap-sd-highspeed" instead)
-
-* broken-cd: as documented in mmc core bindings.
-
 * vmmc-supply: The phandle to the regulator to use for vmmc.  If this is
   specified we'll defer probe until we can find this regulator.