pwm: pwm-tiehrpwm: Update the clock handling of pwm-tiehrpwm
 driver

The clock framework has changed and it's now better to invoke
clock_prepare_enable() and clk_disable_unprepare() rather than the
legacy clk_enable() and clk_disable() calls. This patch converts the
pwm-tiehrpwm driver to the new framework.

Signed-off-by: Philip Avinash <avinashphilip@ti.com>
ARM: AM33XX: clk: Add clock node for EHRPWM TBCLK

EHRPWM module requires explicit clock gating of TBCLK from control
module. Hence add TBCLK clock node in clock tree for EHRPWM modules.

Signed-off-by: Philip, Avinash <avinashphilip@ti.com>
ARM: dts: AM33XX: Add PWMSS device tree nodes

Add PWMSS device tree nodes in relation with ECAP & EHRPWM DT nodes to
AM33XX SoC family. Also populates device tree nodes for ECAP & EHRPWM by
adding necessary properties like pwm-cells, base reg & set disabled as
status.

Signed-off-by: Philip, Avinash <avinashphilip@ti.com>
Reviewed-by: Thierry Reding <thierry.reding@avionic-design.de>
ARM: dts: AM33XX: Add PWM backlight DT data to am335x-evm

PWM output from ecap0 uses as backlight source. Also adds low threshold
value to have a uniform divisions in brightness-levels scales.

Signed-off-by: Philip, Avinash <avinashphilip@ti.com>
Reviewed-by: Thierry Reding <thierry.reding@avionic-design.de>
ARM: dts: AM33XX: Add PWM backlight DT data to am335x-evmsk

PWM output from ecap2 uses as backlight source. Also adds low threshold
value to have a uniform divisions in brightness-levels scales with
inverse polarity.

Signed-off-by: Philip, Avinash <avinashphilip@ti.com>
Reviewed-by: Thierry Reding <thierry.reding@avionic-design.de>