mthca_user.h is unused since commit 486f60954c ("IB/mthca: Move user vendor structures")
Remove it from tree.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>