Add a dedicated ramdisk entry for the octeon bootloader to reduce

the size of the "boot" file.
OK deraadt@

src/etc/etc.octeon/disktab

@@ -1,10 +1,15 @@
-# $OpenBSD: disktab,v 1.3 2015/08/14 23:45:56 krw Exp $
+# $OpenBSD: disktab,v 1.4 2019/07/28 15:41:52 visa Exp $
 
 rdroot|ramdiskroot|RAM-disk root FS image:\
 	:dt=rdroot:se#512:nc#20:nt#4:ns#128:\
 	:ta=4.2BSD:oa#0:pa#10240:fa#512:ba#4096:\
 	:ob#0:pb#0:oc#0:pc#10240:
 
+rdboot|Bootloader image:\
+	:dt=rdroot:se#512:nc#1:nt#16:ns#128:\
+	:ta=4.2BSD:oa#0:pa#2048:fa#512:ba#4096:\
+	:ob#0:pb#0:oc#0:pc#2048:
+
 miniroot|Installation root FS image:\
 	:dt=rdroot:se#512:nc#9:nt#16:ns#128:\
 	:oc#0:pc#24576: