[XFS] kill xfs_mount_init

xfs_mount_init is inlined into xfs_fs_fill_super and allocation switched
to kzalloc. Plug a leak of the mount structure for most early mount
failures. Move xfs_icsb_init_counters to as late as possible in the mount
path and make sure to undo it so that no stale hotplug cpu notifiers are
left around on mount failures.

SGI-PV: 981951
SGI-Modid: xfs-linux-melb:xfs-kern:31196a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>