iget: stop HFSPLUS from using iget() and read_inode()

Stop the HFSPLUS filesystem from using iget() and read_inode().  Replace
hfsplus_read_inode() with hfsplus_iget(), and call that instead of iget().
hfsplus_iget() then uses iget_locked() directly and returns a proper error
code instead of an inode in the event of an error.

hfsplus_fill_super() returns any error incurred when getting the root inode.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>