Remove a pre-tier-1 kernel compatability helper. This means a 6.x loader

won't boot a pre-5.1 development amd64 kernel.  That's no big loss though.

sys/boot/i386/libi386/biossmap.c

@@ -103,6 +103,4 @@ bios_addsmapdata(struct preloaded_file *kfp)
 		return;
 	len = smaplen * sizeof(*smapbase);
 	file_addmetadata(kfp, MODINFOMD_SMAP, len, smapbase);
-	/* Temporary compatability with older development kernels */
-	file_addmetadata(kfp, 0x0009, len, smapbase);
 }