dtc: fix issue caused by GCC 10.x defaulting to -fno-common

After changing from -fcommon which was the default in earlier gcc
releases, the dtc native build failed due to multiple declarations
of the form 'YYLTYPE yylloc'. Two of the declarations were removed,
which fixed the problem.

scripts/dtc/dtc-lexer.l

@@ -38,7 +38,6 @@ LINECOMMENT	"//".*\n
 #include "srcpos.h"
 #include "dtc-parser.tab.h"
 
-YYLTYPE yylloc;
 extern bool treesource_error;
 
 /* CAUTION: this will stop working if we ever use yyless() or yyunput() */

scripts/dtc/dtc-lexer.lex.c_shipped

@@ -631,7 +631,6 @@ char *yytext;
 #include "srcpos.h"
 #include "dtc-parser.tab.h"
 
-YYLTYPE yylloc;
 extern bool treesource_error;
 
 /* CAUTION: this will stop working if we ever use yyless() or yyunput() */