edid: add edid_get_timing_validate() variant to filter out edid modes

The original edid_get_timing() function returns the first valid timing,
but on some plaforms, we could only supports a subset of the listed
monitot's navite timing.

Let's introduce a edid_get_timing_validate() adding a mode_valid callback
including a private cookie pointer.

If the callback returns false, the current timing is discared and the next
one is checked. If no valid & supported timings are found, the function
would return an error.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/common/edid.c b/common/edid.c
index 90d1167..f244d26 100644
--- a/common/edid.c
+++ b/common/edid.c
@@ -168,8 +168,12 @@
 	return false;
 }
 
-int edid_get_timing(u8 *buf, int buf_size, struct display_timing *timing,
-		    int *panel_bits_per_colourp)
+int edid_get_timing_validate(u8 *buf, int buf_size,
+			     struct display_timing *timing,
+			     int *panel_bits_per_colourp,
+			     bool (*mode_valid)(void *priv,
+					const struct display_timing *timing),
+			     void *mode_valid_priv)
 {
 	struct edid1_info *edid = (struct edid1_info *)buf;
 	bool timing_done;
@@ -193,7 +197,11 @@
 		desc = &edid->monitor_details.descriptor[i];
 		if (desc->zero_flag_1 != 0) {
 			decode_timing((u8 *)desc, timing);
-			timing_done = true;
+			if (mode_valid)
+				timing_done = mode_valid(mode_valid_priv,
+							 timing);
+			else
+				timing_done = true;
 			break;
 		}
 	}
@@ -225,6 +233,14 @@
 	return 0;
 }
 
+int edid_get_timing(u8 *buf, int buf_size, struct display_timing *timing,
+		    int *panel_bits_per_colourp)
+{
+	return edid_get_timing_validate(buf, buf_size, timing,
+					panel_bits_per_colourp, NULL, NULL);
+}
+
+
 /**
  * Snip the tailing whitespace/return of a string.
  *