drm/v3d: Replace wait_for macros to remove use of msleep

drm/v3d: Replace wait_for macros to remove use of msleep

The wait_for macro's for Broadcom V3D driver used msleep, which is
inappropriate due to its inaccuracy at low values (minimum wait time
is about 30ms on the Raspberry Pi).  This sleep was triggering in
v3d_clean_caches(), causing us to only be able to dispatch ~33 compute
jobs per second.

This patch replaces the macro with the one from the Intel i915 version
which uses usleep_range to provide more accurate waits.

v2: Split from the vc4 patch so that we can confidently apply to
    stable (by anholt)

Signed-off-by: James Hughes <james.hughes@raspberrypi.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200217153145.13780-1-james.hughes@raspberrypi.com
Link: https://github.com/raspberrypi/linux/issues/3460
Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+")