HID keyboard polling interval

[seemefirst@gamil.com]

On stm32 port HID keyboard is slow. In current condition, you have to put at least 10ms delay before and after each characters to send out characters. In order to improve this I have reduced the polling interval from 8ms to 1ms and safely sent out characters with 2ms delays. This is 5 times faster. We can define something like MICROPY_HW_HID_POLLING_INTERVAL in mpconfigboard to add this.
What do you think?

[jimmo]

Sounds good! Definitely worth sending a PR

[seemefirst@gamil.com]

sure.