checksum: fixes on specific NED-only checksum inserters/checkers

Author: avarga

src/inet/protocolelement/checksum/Crc32HeaderChecker.ned

@@ -13,6 +13,4 @@ simple Crc32HeaderChecker extends ChecksumHeaderChecker
 {
     parameters:
         checksumType = "crc32";
-        string headerPosition @enum("front","back") = default("front");
-        @class(CrcHeaderInserter);
 }

src/inet/protocolelement/checksum/Crc32HeaderInserter.ned

@@ -13,6 +13,4 @@ simple Crc32HeaderInserter extends ChecksumHeaderInserter
 {
     parameters:
         checksumType = "crc32";
-        string headerPosition @enum("front","back") = default("front");
-        @class(CrcHeaderInserter);
 }

src/inet/protocolelement/checksum/InternetChecksumHeaderChecker.ned

@@ -7,12 +7,10 @@
 
 package inet.protocolelement.checksum;
 
-import inet.protocolelement.checksum.ChecksumHeaderInserter;
+import inet.protocolelement.checksum.ChecksumHeaderChecker;
 
-simple InternetChecksumHeaderChecker extends ChecksumHeaderInserter
+simple InternetChecksumHeaderChecker extends ChecksumHeaderChecker
 {
     parameters:
         checksumType = "internet";
-        string headerPosition @enum("front","back") = default("front");
-        @class(CrcHeaderInserter);
 }

src/inet/protocolelement/checksum/InternetChecksumHeaderInserter.ned

@@ -13,6 +13,4 @@ simple InternetChecksumHeaderInserter extends ChecksumHeaderInserter
 {
     parameters:
         checksumType = "internet";
-        string headerPosition @enum("front","back") = default("front");
-        @class(CrcHeaderInserter);
 }