lxd/daemon/storage: Renames daemonStorageUnmount to daemonStorageVolumesUnmount
lxd/daemon/storage: Renames daemonStorageUnmount to daemonStorageVolumesUnmount

And removes the storage pool unmount functionality, as we don't always want to do that at the same time as unmounting the daemon volumes.

Signed-off-by: Thomas Parrott <6b778ce645fb0e3dde76d79eccad490955b1ae74@canonical.com>

hallyn/lxd,hallyn/lxd,hallyn/lxd,stgraber/lxd,hallyn/lxd,atxwebs/lxd,stgraber/lxd,atxwebs/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,atxwebs/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,hallyn/lxd,lxc/lxd,atxwebs/lxd,stgraber/lxd,lxc/lxd