xfs: wrap inode creation dqalloc calls

xfs: wrap inode creation dqalloc calls

Create a helper that calls dqalloc to allocate and grab a reference to
dquots for the user, group, and project ids listed in an icreate
structure.  This simplifies the creat-related dqalloc callsites
scattered around the code base.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>