drivers/sensor/hp206c: Clarify tick rate warning

The default tick rate is now 10 kHz, but that driver was demanding
that it be exactly 1 kHz instead of at least that rate.  I checked the
source, and the driver isn't actually extracting "ticks" from the
kernel illegally, it just needs fine-grained timers that work with the
existing millisecond API.  Let it build, this is fine.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>