drm/modes: Handle reflect_[xy] in the middle of the cmd line

The command line parser was looking for an "=" before the ","
separator.
If the command line had reflect_[xy] before another option
which took a parameter, it would find the "=" from the second
option and assume it was associated with the reflect option,
generally leading to a parsing failure.

Handle this case by looking for both "," and "=", and taking
the first instance.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

Author: 6by9

drivers/gpu/drm/drm_modes.c

@@ -2173,12 +2173,15 @@ static int drm_mode_parse_cmdline_options(const char *str,
 
 	option = str;
 	do {
+		sep = strchr(option, ',');
 		delim = strchr(option, '=');
 		if (!delim) {
-			delim = strchr(option, ',');
-
-			if (!delim)
+			if (!sep)
 				delim = option + strlen(option);
+			else
+				delim = sep;
+		} else if (sep && sep < delim) {
+			delim = sep;
 		}
 
 		if (!strncmp(option, "rotate", delim - option)) {