dt-bindings: nvmem: imx-ocotp: add compatible string for imx6sll

Add new compatible string for i.MX6SLL SOC.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/nvmem/imx-ocotp.txt

 Freescale i.MX6 On-Chip OTP Controller (OCOTP) device tree bindings
 
 This binding represents the on-chip eFuse OTP controller found on
-i.MX6Q/D, i.MX6DL/S, i.MX6SL, i.MX6SX and i.MX6UL SoCs.
+i.MX6Q/D, i.MX6DL/S, i.MX6SL, i.MX6SX, i.MX6UL and i.MX6SLL SoCs.
 
 Required properties:
 - compatible: should be one of
@@ -10,6 +10,7 @@ Required properties:
 	"fsl,imx6sx-ocotp" (i.MX6SX),
 	"fsl,imx6ul-ocotp" (i.MX6UL),
 	"fsl,imx7d-ocotp" (i.MX7D/S),
+	"fsl,imx6sll-ocotp" (i.MX6SLL),
 	followed by "syscon".
 - #address-cells : Should be 1
 - #size-cells : Should be 1