mspm0: add simple pwm driver

[Iooon]

The implementation is based on the stm32 simple_pwm API and implemented against the TI MSPM0 SDK register sequence.

• Up to 4 CCP channels per timer, each with a PwmPin
• Edge-aligned and center-aligned counting modes
• Configurable frequency and clock source (LFCLK / MFCLK)
• Per-channel duty cycle: raw, fraction, percent, fully on/off
• Per-channel enable/disable and output polarity
• embedded-hal SetDutyCycle impl
• Examples for mspm0g3507 and mspm0l1306 (the boards I can test with)

[i509VCB]

Give me a few days to get some info about the pwm driver I've already written. Hopefully can release it in a few days.

[Iooon]

Give me a few days to get some info about the pwm driver I've already written. Hopefully can release it in a few days.

Ah damn, sorry. I probably should have checked. Did not want to double the work.

[i509VCB]

Give me a few days to get some info about the pwm driver I've already written. Hopefully can release it in a few days.

Ah damn, sorry. I probably should have checked. Did not want to double the work.

The pwm driver in my case also allows 32-bit counting (if timer supports it) and building a 2/4 channel version. Probably also good to have this as a reference to make sure I didn't miss anything.

Edit: also completely type erased T out of the SimplePwmChannel type