Adds a PWM lower-half for EPWM0 and EPWM1, covering both output channels of
each. The CTRL_MMR EPWM clock enables are unlocked once during board bring-up.
t3-gem-o1 registers /dev/pwm0 and /dev/pwm1 with PWM_NCHANNELS=2.
Verified on t3-gem-o1: all four outputs (EPWM0 A+B, EPWM1 A+B) drive physical
pins, jumpered into a Linux GPIO input -- 50% and 20% duty read back at the
expected sample ratios, and gpiomon timed a 50 Hz half-period at 9.998-10.002
ms. examples/pwm starts and stops a 1 kHz train cleanly.
Assisted-by: Claude Code:claude-fable-5
Signed-off-by: Ulaş Sertan Kemeç <sertan.usk@gmail.com>