drm/i915/icl: don't set CNL_DDI_CLOCK_REG_ACCESS_ON anymore

drm/i915/icl: don't set CNL_DDI_CLOCK_REG_ACCESS_ON anymore

The new recommendation from the spec is to simply not set this bit
anymore. Not setting the bit would prevent some hangs that our driver
manages to avoid since commit ad475413a3ac ("drm/i915: enable the
pipe/transcoder/planes later on HSW+"), and the theoretical downside
of not setting the bit doesn't seem realistic according to the HW
team. Let's follow their recommendation.

BSpec: 20233
References: commit ad475413a3ac ("drm/i915: enable the
 pipe/transcoder/planes later on HSW+")
Cc: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180726001229.13791-1-paulo.r.zanoni@intel.com