Add cpu transcoder attribute to intel dp

Also, used this attribute in the calculation of htotal and other registers
Added intel_dp_* functions for m,n registers and dimension register calculations

Change-Id: I99dd7156700d59b0b4c85e34c9aa1c6408c7f31a
Reviewed-on: https://gerrit.chromium.org/gerrit/64001
Reviewed-by: Ronald G. Minnich <rminnich@chromium.org>
Commit-Queue: Furquan Shaikh <furquan@chromium.org>
Tested-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/4422
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/drivers/intel/gma/intel_ddi.c

@@ -223,3 +223,11 @@ u32 intel_ddi_calc_transcoder_flags(u32 pipe_bpp,
 
 	return temp;
 }
+
+enum transcoder intel_ddi_get_transcoder(enum port port,
+					 enum pipe pipe)
+{
+	if (port == PORT_A)
+		return TRANSCODER_EDP;
+	return (enum transcoder)pipe;
+}