ceph-disk: encapsulate partprobe / partx calls

Add the update_partition function to reduce code duplication.
The action is made an argument although it always is -a because it will
be -d when deleting a partition.

Use the update_partition function in prepare_journal_dev

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
(cherry picked from commit 922a15ea6865ef915bbdec2597433da6792c1cb2)

Conflicts:
	src/ceph-disk
ceph-disk: run partprobe after zap

Not running partprobe after zapping a device can lead to the following:

* ceph-disk prepare /dev/loop2
* links are created in /dev/disk/by-partuuid
* ceph-disk zap /dev/loop2
* links are not removed from /dev/disk/by-partuuid
* ceph-disk prepare /dev/loop2
* some links are not created in /dev/disk/by-partuuid

This is assuming there is a bug in the way udev events are handled by
the operating system.

http://tracker.ceph.com/issues/9665 Fixes: #9665

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
(cherry picked from commit fed3b06c47a5ef22cb3514c7647544120086d1e7)
ceph-disk: use update_partition in prepare_dev and main_prepare

In the case of prepare_dev the partx alternative was missing and is not
added because update_partition does it.

http://tracker.ceph.com/issues/9721 Fixes: #9721

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
(cherry picked from commit 23e71b1ee816c0ec8bd65891998657c46e364fbe)

Conflicts:
	src/ceph-disk
Merge pull request #3015 from dachary/wip-9665-ceph-disk-partprobe-dumpling

ceph disk zap must call partprobe