dtc: Set "noinput" in the lexer to avoid an unused function

Regenerate the corresponding generated lexer.

Regenerating the lexer with current flex also provides prototypes for
various yy* functions, making some -Wmissing-prototypes warnings go away
as well.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>

scripts/dtc/dtc-lexer.l

@@ -18,7 +18,7 @@
  *                                                                   USA
  */
 
-%option noyywrap nounput yylineno
+%option noyywrap noinput nounput yylineno
 
 %x INCLUDE
 %x BYTESTRING