drivers/fpga: ice40: use microsecond resolution for reset time

The 200ns reset time specified in the datasheet are a minimum time; and the
nanoseconds were being rounded to whole microseconds anyway.

Also make it the same type as `config_delay_us` (`uint16_t`).

Signed-off-by: Armin Brauns <armin.brauns@embedded-solutions.at>
2 files changed