xfs: Start using pquotaino from the superblock.

Start using pquotino and define a macro to check if the
superblock has pquotino.

Keep backward compatibilty by alowing mount of older superblock
with no separate pquota inode.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --cc fs/xfs/xfs_mount.c
Simple merge

diff --cc fs/xfs/xfs_qm.c
Simple merge

diff --cc fs/xfs/xfs_qm_syscalls.c
Simple merge

diff --cc fs/xfs/xfs_sb.h
Simple merge

diff --cc fs/xfs/xfs_super.c
Simple merge