mis-definition of SLEWCTRL_FAST in dt-bindings amxxxx header

["Peter A. Bigot" <pab@pabigot.com>]

While converting some old DTS bindings, I noticed that the Linux 
include/dt-bindings/pinctrl/am33xx.h and am43xx.h headers both define 
SLEWCTRL_FAST constants:

include/dt-bindings/pinctrl/am33xx.h:#define SLEWCTRL_FAST              
(1 << 6)
include/dt-bindings/pinctrl/am43xx.h:#define SLEWCTRL_FAST              
(1 << 19)

According to the TRM for these processors, the effect of setting that 
bit is to select slow slew; fast would be selected by leaving it 
cleared.  The constants should therefore be named SLEWCTRL_SLOW.

This is consistent with the value for the I2C binding constants I'm 
converting:

beagleboard/3.14:arch/arm/boot/dts/am335x-bone-common-pinmux.dtsi: 0x158 
0x72      /* spi0_d1.i2c1_sda, SLEWCTRL_SLOW | INPUT_PULLUP | MODE2 */
beagleboard/3.14:arch/arm/boot/dts/am335x-bone-common-pinmux.dtsi: 0x15c 
0x72      /* spi0_cs0.i2c1_scl, SLEWCTRL_SLOW | INPUT_PULLUP | MODE2 */

except that in the official files we have something like:

stable/linux-3.14.y:arch/arm/boot/dts/am43x-epos-evm.dts: 0x188 
(PIN_INPUT_PULLUP | SLEWCTRL_FAST | MUX_MODE0)    /* i2c0_sda.i2c0_sda */
stable/linux-3.14.y:arch/arm/boot/dts/am43x-epos-evm.dts: 0x18c 
(PIN_INPUT_PULLUP | SLEWCTRL_FAST | MUX_MODE0)    /* i2c0_scl.i2c0_scl */

which is either wrong or misleading.

Peter