mm/hmm: add missing call to hmm_range_need_fault() before returning EFAULT

All return paths that do EFAULT must call hmm_range_need_fault() to
determine if the user requires this page to be valid.

If the page cannot be made valid if the user later requires it, due to vma
flags in this case, then the return should be HMM_PFN_ERROR.

Fixes: a3e0d41c ("mm/hmm: improve driver API to work and wait over a range")
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>