dt: Document: correct tegra20/30 pinctrl slew-rate name

change nvidia,slew_rate* to nvidia,slew-rate*

Cc: stable@kernel.org
Signed-off-by: NPritesh Raithatha <praithatha@nvidia.com>
Acked-by: NStephen Warren <swarren@nvidia.com>
Tested-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/pinctrl/nvidia,tegra20-pinmux.txt

@@ -93,7 +93,7 @@ Valid values for pin and group names are:
 
     With some exceptions, these support nvidia,high-speed-mode,
     nvidia,schmitt, nvidia,low-power-mode, nvidia,pull-down-strength,
-    nvidia,pull-up-strength, nvidia,slew_rate-rising, nvidia,slew_rate-falling.
+    nvidia,pull-up-strength, nvidia,slew-rate-rising, nvidia,slew-rate-falling.
 
     drive_ao1, drive_ao2, drive_at1, drive_at2, drive_cdev1, drive_cdev2,
     drive_csus, drive_dap1, drive_dap2, drive_dap3, drive_dap4, drive_dbg,

Documentation/devicetree/bindings/pinctrl/nvidia,tegra30-pinmux.txt

@@ -83,7 +83,7 @@ Valid values for pin and group names are:
   drive groups:
 
     These all support nvidia,pull-down-strength, nvidia,pull-up-strength,
-    nvidia,slew_rate-rising, nvidia,slew_rate-falling. Most but not all
+    nvidia,slew-rate-rising, nvidia,slew-rate-falling. Most but not all
     support nvidia,high-speed-mode, nvidia,schmitt, nvidia,low-power-mode.
 
     ao1, ao2, at1, at2, at3, at4, at5, cdev1, cdev2, cec, crt, csus, dap1,