drm/i915/icl: Fix setting 10 bit deep color mode

There is a bug in hdmi_deep_color_possible() - we compare pipe_bpp
<= 8*3 which returns true every time for hdmi_deep_color_possible 12 bit
deep color mode test in intel_hdmi_compute_config().(Even when the
requested color mode is 10 bit through max bpc property)

Comparing pipe_bpp with bpc * 3 takes care of this condition where
requested max bpc is 10 bit, so hdmi_deep_color_possible with 12 bit
returns false when requested max bpc is 10.(Ville)

v2:Add suggested by Ville Syrjälä

Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Aditya Swarup <aditya.swarup@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Clinton Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190507181856.16091-1-aditya.swarup@intel.com