[PATCH] nfsd: sign conversion obscuring errors in nfsd_set_posix_acl()

Assigning the result of posix_acl_to_xattr() to an unsigned data type
(size/size_t) obscures possible errors.

Coverity CID: 1206.

Signed-off-by: Florin Malita <fmalita@gmail.com>
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>