drm/i915/glk: Reuse broxton code for geminilake

Geminilake is mostly backwards compatible with broxton, so change most
of the IS_BROXTON() checks to IS_GEN9_LP(). Differences between the
platforms will be implemented in follow-up patches.

v2: Don't reuse broxton's path in intel_update_max_cdclk().
    Don't set plane count as in broxton.

v3: Rebase

v4: Include the check intel_bios_is_port_hpd_inverted().
    Commit message.

v5: Leave i915_dmc_info() out; glk's csr version != bxt's. (Rodrigo)

v6: Rebase.

v7: Convert a few mode IS_BROXTON() occurances in pps, ddi, dsi and pll
    code. (Rodrigo)

v8: Squash a couple of DDI patches with more conversions. (Rodrigo)

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1480667037-11215-2-git-send-email-ander.conselvan.de.oliveira@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -3256,7 +3256,7 @@ enum skl_disp_power_wells {
 #define INTERVAL_1_33_US(us)	(((us) * 3)   >> 2)
 #define INTERVAL_0_833_US(us)	(((us) * 6) / 5)
 #define GT_INTERVAL_FROM_US(dev_priv, us) (IS_GEN9(dev_priv) ? \
-				(IS_BROXTON(dev_priv) ? \
+				(IS_GEN9_LP(dev_priv) ? \
 				INTERVAL_0_833_US(us) : \
 				INTERVAL_1_33_US(us)) : \
 				INTERVAL_1_28_US(us))
@@ -3265,7 +3265,7 @@ enum skl_disp_power_wells {
 #define INTERVAL_1_33_TO_US(interval)  (((interval) << 2) / 3)
 #define INTERVAL_0_833_TO_US(interval) (((interval) * 5)  / 6)
 #define GT_PM_INTERVAL_TO_US(dev_priv, interval) (IS_GEN9(dev_priv) ? \
-                           (IS_BROXTON(dev_priv) ? \
+                           (IS_GEN9_LP(dev_priv) ? \
                            INTERVAL_0_833_TO_US(interval) : \
                            INTERVAL_1_33_TO_US(interval)) : \
                            INTERVAL_1_28_TO_US(interval))