drm/i915: Fix DP_AUX_CH_CTL_TIME_OUT naming

Rename DP_AUX_CH_CTL_TIME_OUT_1600us to DP_AUX_CH_CTL_TIME_OUT_MAX, as
the meaning of the (3 << 26) value varies per platform, but it's always the
maximum timeout for that platform. Pre-CNL it means 1600us, and for CNL
it means 3200us.

v2:
-Split in to two patches (Rodrigo)

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: James Ausmus <james.ausmus@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171012213037.4245-1-james.ausmus@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -5242,7 +5242,7 @@ enum {
 #define   DP_AUX_CH_CTL_TIME_OUT_400us	    (0 << 26)
 #define   DP_AUX_CH_CTL_TIME_OUT_600us	    (1 << 26)
 #define   DP_AUX_CH_CTL_TIME_OUT_800us	    (2 << 26)
-#define   DP_AUX_CH_CTL_TIME_OUT_1600us	    (3 << 26)
+#define   DP_AUX_CH_CTL_TIME_OUT_MAX	    (3 << 26) /* Varies per platform */
 #define   DP_AUX_CH_CTL_TIME_OUT_MASK	    (3 << 26)
 #define   DP_AUX_CH_CTL_RECEIVE_ERROR	    (1 << 25)
 #define   DP_AUX_CH_CTL_MESSAGE_SIZE_MASK    (0x1f << 20)

drivers/gpu/drm/i915/intel_dp.c

@@ -1032,7 +1032,7 @@ static uint32_t skl_get_aux_send_ctl(struct intel_dp *intel_dp,
 	       DP_AUX_CH_CTL_DONE |
 	       (has_aux_irq ? DP_AUX_CH_CTL_INTERRUPT : 0) |
 	       DP_AUX_CH_CTL_TIME_OUT_ERROR |
-	       DP_AUX_CH_CTL_TIME_OUT_1600us |
+	       DP_AUX_CH_CTL_TIME_OUT_MAX |
 	       DP_AUX_CH_CTL_RECEIVE_ERROR |
 	       (send_bytes << DP_AUX_CH_CTL_MESSAGE_SIZE_SHIFT) |
 	       DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(32) |