drm/i915/gt: Use proper sleeping functions for timeouts shorter than 20ms

msleep is very imprecise for timeouts shorter than 20
milliseconds and most probably will sleep longer. Use
uslee_range() instead.

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Sebastian Brzezinka <sebastian.brzezinka@intel.com>
Reviewed-by: Krzysztof Karas <krzysztof.karas@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250314021225.11813-5-andi.shyti@linux.intel.com