checkpatch: Check to make sure DT property names are lowercase

Property names in DT files should be lowercase. Reports an error
if a property name that has uppercase characters in it is detected.
See following imaginary example:

qcom,venus@aae0000 {
	...
	ClockNames = "core_clk", "iface_clk", "bus_clk";
	...
};

"ClockNames" here is an invalid property name as it contains uppercase
characters.

Change-Id: I8f05e0daa84bc18b95e307c3733d4700ae7fe1b0
Signed-off-by: Prathyush Katukojwala <pkatukoj@codeaurora.org>
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 4909abc..e6e7117 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2964,12 +2964,17 @@
 		next if ($realfile !~ /\.(h|c|s|S|pl|sh|dtsi|dts)$/);
 
 # do DT checks:
+#       * Property names should be lower-case
 #       * Only newline after };
 
 		if ($realfile =~ /\.(dts|dtsi)$/ && $line =~ /^\+/) {
 			if($line =~ /\};.+$/) { # check for any characters after };
 				ERROR("DT_STYLE", "newline does not follow immediately after };\n" . $herecurr);
 			}
+
+			if($line =~ /[0-9a-zA-Z,\._\+\?#]+\s*=/ && $line !~ /[0-9a-z,\._\+\?#]+\s*=/) { # find property names with uppercase characters
+				ERROR("DT_PROPERTY_NAME", "property name is not lowercase\n" . $herecurr);
+			}
 		}
 
 # line length limit (with some exclusions)