Revert "checkpolicy: Redo filename/filesystem syntax to support filename trans rules"

This reverts commit d72a9ec825ef2a8723510f62292cf2adfd4a2a6c.  It should
never have been added.  It breaks the correct wrapping of filenames in "
diff --git a/checkpolicy/policy_scan.l b/checkpolicy/policy_scan.l
index a61e0db..5ee27f8 100644
--- a/checkpolicy/policy_scan.l
+++ b/checkpolicy/policy_scan.l
@@ -222,16 +222,13 @@
 permissive |
 PERMISSIVE			{ return(PERMISSIVE); }
 "/"({alnum}|[_\.\-/])*	        { return(PATH); }
+\"({alnum}|[_\.\-])+\"			{ return(FILENAME); }
 {letter}({alnum}|[_\-])*([\.]?({alnum}|[_\-]))*	{ return(IDENTIFIER); }
+{alnum}*{letter}{alnum}*        { return(FILESYSTEM); }
 {digit}+|0x{hexval}+            { return(NUMBER); }
 {digit}{1,3}(\.{digit}{1,3}){3}    { return(IPV4_ADDR); }
 {hexval}{0,4}":"{hexval}{0,4}":"({hexval}|[:.])*  { return(IPV6_ADDR); }
 {digit}+(\.({alnum}|[_.])*)?    { return(VERSION_IDENTIFIER); }
-\"({alnum}|[_\.\-])+\"		{ return(FILENAME); }
-{alnum}*                        { return(FILENAME); }
-\.({alnum}|[_\.\-])*	        { return(FILENAME); }
-{letter}+([-_\.]|{alnum})+      { return(FILENAME); }
-([_\.]){alnum}+                 { return(FILENAME); }
 #line[ ]1[ ]\"[^\n]*\"		{ set_source_file(yytext+9); }
 #line[ ]{digit}+	        { source_lineno = atoi(yytext+6)-1; }
 #[^\n]*                         { /* delete comments */ }