[vim] remove vim expandtab comments on most of the files

tools/liblkboot.c

@@ -321,5 +321,3 @@ out:
         close(fd_out);
     return ret;
 }
-
-// vim: noexpandtab

tools/lkboot.c

@@ -122,5 +122,3 @@ int main(int argc, char **argv)
     }
     return lkboot_txn(host, cmd, fd, args);
 }
-
-// vim: noexpandtab

tools/mkimage.c

@@ -148,5 +148,3 @@ int main(int argc, char **argv)
     close(fd);
     return 0;
 }
-
-// vim: set noexpandtab:

tools/network.c

@@ -125,5 +125,3 @@ int tcp_connect(in_addr_t addr, unsigned port)
 {
     return inet_connect(addr, SOCK_STREAM, port);
 }
-
-// vim: noexpandtab