pinctrl: remove slew-rate parameter from tz1090

As the binding for slew-rate is under discussion and seems to need
more tought it will get removed for now, so it doesn't get an offical
release.

Therefore remove it again from the only current user, tz1090.

Signed-off-by: Heiko Stuebner <[e-mail]>
Reviewed-by: James Hogan <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

Documentation/devicetree/bindings/pinctrl/img,tz1090-pdc-pinctrl.txt

···
   - bias-pull-down
   - input-schmitt-enable
   - input-schmitt-disable
-  - slew-rate: Integer, control slew rate of pins.
-      0: slow (half frequency)
-      1: fast
   - drive-strength: Integer, control drive strength of pins in mA.
       2: 2mA
       4: 4mA
···
 
   drive groups:
 
-    These support input-schmitt-enable, input-schmitt-disable, slew-rate,
+    These support input-schmitt-enable, input-schmitt-disable,
     drive-strength, low-power-enable, and low-power-disable.
 
     pdc

Documentation/devicetree/bindings/pinctrl/img,tz1090-pinctrl.txt

···
   - bias-pull-down
   - input-schmitt-enable
   - input-schmitt-disable
-  - slew-rate: Integer, control slew rate of pins.
-      0: slow (half frequency)
-      1: fast
   - drive-strength: Integer, control drive strength of pins in mA.
       2: 2mA
       4: 4mA
···
         function:              afe, ts_out_0.
         input-schmitt-enable:  supported.
         input-schmitt-disable: supported.
-        slew-rate:             supported.
         drive-strength:        supported.
     pdm_d
         pins:                  pdm_d.
···
                                lcd_trace, phy_ringosc.
         input-schmitt-enable:  supported.
         input-schmitt-disable: supported.
-        slew-rate:             supported.
         drive-strength:        supported.
 
   drive groups:
 
-    These all support input-schmitt-enable, input-schmitt-disable, slew-rate,
+    These all support input-schmitt-enable, input-schmitt-disable,
     and drive-strength.
 
     jtag

drivers/pinctrl/pinctrl-tz1090-pdc.c

···
 		*width = 1;
 		*map = tz1090_pdc_boolean_map;
 		break;
-	case PIN_CONFIG_SLEW_RATE:
-		*shift = REG_GPIO_CONTROL2_PDC_SR_S;
-		*width = 1;
-		*map = tz1090_pdc_boolean_map;
-		break;
 	case PIN_CONFIG_DRIVE_STRENGTH:
 		*shift = REG_GPIO_CONTROL2_PDC_DR_S;
 		*width = 2;

drivers/pinctrl/pinctrl-tz1090.c

···
 		*width = 1;
 		*map = tz1090_boolean_map;
 		break;
-	case PIN_CONFIG_SLEW_RATE:
-		*reg = REG_PINCTRL_SR;
-		*width = 1;
-		*map = tz1090_boolean_map;
-		break;
 	case PIN_CONFIG_DRIVE_STRENGTH:
 		*reg = REG_PINCTRL_DR;
 		*width = 2;