pwm: pwm-omap-dmtimer: Adapt driver to utilize dmtimer pdata ops

Adapt driver to utilize dmtimer pdata ops instead of pdata-quirks.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>