drivers: hp206 driver does not need 2000 ticks/s frequency

From code inspection, the driver always took timeouts in milliseconds.
The only sub-ms wait uses k_busy_wait(), which has microseconds
granularity, but its granularity does not depend on the system clock
tick rate.

Change-Id: If48363fd1fbeeb8e5ff0f0f2ca86e671d63bc571
Signed-off-by: Benjamin Walsh <benjamin.walsh@windriver.com>