Remove FS_Read2().

Functionally the same as FS_Read().
Streaming functionality was removed in https://github.com/ioquake/ioq3/commit/672cfbf16f83fb67f6ce9bb1d3571dc32a5b3083 but flag remained.

code/qcommon/md5.c

@@ -290,7 +290,7 @@ char *Com_MD5File( const char *fn, int length, const char *prefix, int prefix_le
 		MD5Update(&md5 , (unsigned char *)prefix, prefix_len);
 
 	for(;;) {
-		r = FS_Read2(buffer, sizeof(buffer), f);
+		r = FS_Read(buffer, sizeof(buffer), f);
 		if(r < 1)
 			break;
 		if(r + total > length)