Increase reserved space at start of image from 4MB to 16MB to make room

for Rockchip bootloaders.

distrib/utils/embedded/conf/evbarm.conf

@@ -1,4 +1,4 @@
-# $NetBSD: evbarm.conf,v 1.27 2017/05/13 10:44:58 hubertf Exp $
+# $NetBSD: evbarm.conf,v 1.28 2018/06/19 15:12:05 jmcneill Exp $
 # evbarm shared config
 #
 image=$HOME/${board}.img
@@ -7,7 +7,7 @@ MACHINE=evbarm
 
 swap=256
 extra=48		# spare space
-init=8
+init=32
 boot=$((192 - ${init}))
 ffsoffset=$(( (${init} + ${boot} + ${swap}) / 2 ))m