drm/vc4: hvs: Boost the core clock during modeset

drm/vc4: hvs: Boost the core clock during modeset

In order to prevent timeouts and stalls in the pipeline, the core clock
needs to be maxed at 500MHz during a modeset on the BCM2711.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/37ed9e0124c5cce005ddc8dafe821d8b0da036ff.1599120059.git-series.maxime@cerno.tech
[hoegeun.kwon: A screen cracking problem occurs in FHD(1920x1080). The
cause is that the clock should be kept at 500MHz, but it occurred when
the clock fell to 200MHz, so apply a patch.]
Signed-off-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Change-Id: Ie0d4880966c1644bfdf56bb49dbb82559978538c