pwm: ti: am33xx: Enable Auxiliary PWM using eCAP

pwm: ti: am33xx: Enable Auxiliary PWM using eCAP

In am33xx SoC[1], enhanced capture (eCAP) supports auxiliary PWM (APWM).
This series adds the PWM driver support for the APWM feature for eCAP on
AM33xx.

eCAP HW also supports the capture mode. Currently, this driver only
supports APWM.

This is based on the Linux kernel driver -> drivers/pwm/pwm-tiecap.c
Version: v6.12

Tested on AM335x EVM[2].

[1] AM335x TRM - https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf
[2] AM335x EVM - https://www.ti.com/tool/TMDXEVM3358

Signed-off-by: Sukrut Bellary <sbellary@baylibre.com>