bus: imx-weim: optionally enable continuous burst clock

To enable continuous burst clock, add "fsl,continuous-burst-clk" along
with "fsl,burst-clk-enable" property to the weim bus's devicetree node.

Example:
weim: weim@21b8000 {
	compatible = "fsl,imx6ul-weim", "fsl,imx6q-weim";
	reg = <0x021b8000 0x4000>;
	clocks = <&clks 143>;
	#address-cells = <2>;
	#size-cells = <1>;
	ranges = <0 0 0x50000000 0x08000000>;
	fsl,weim-cs-gpr = <&gpr>;
	fsl,burst-clk-enable;
	fsl,continuous-burst-clk;

	client-device@0 {
		...
	};
};

Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>