fix braino in fs: do not assign default i_ino in new_inode

usbfs_get_inode() is something completely different...

Bogosity introduced by commit 85fe4025 ("fs: do not assign default
i_ino in new_inode").

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>