This code has been working since 2012, as limiting the time between
1ms and 3ms is unlikely to do any harm.

Soothes checkpatch warning:

  WARNING: msleep < 20ms can sleep for up to 20ms;
      see Documentation/timers/timers-howto.txt
  #161: FILE: drivers/mfd/88pm805.c:161:
  +	msleep(1);
Signed-off-by: Lee Jones <lee.jones@linaro.org>