base-files: change boot & umount STOP indexes

base-files: change boot & umount STOP indexes

This patch is in a series to allow additional STOP indexes after umount,
so that other block devices may stop cleanly.

boot is now STOP=90
umount is now STOP=90

After this patch series, the resulting STOP indexes in the 80s & 90s
will be:

STOP=85 odhcpd.init
STOP=89 conntrackd.init
STOP=89 log.init
STOP=89 rssileds.init
STOP=90 boot
STOP=90 kdump.init
STOP=90 network
STOP=90 sysfixtime
STOP=90 umount
STOP=98 mdadm.init (note: will be addressed in a separate patch)

Signed-off-by: Joseph Tingiris <joseph.tingiris@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
[PKG_RELEASE is now 200]

(cherry picked from commit 04811007e53c5a5bdddbd0a00b330e12a5dbd045)