This is a step toward eliminating uverbs_cmd_mask. Preset this list in the
core code. Only the op reg_user_mr wasn't already being required from the
drivers.

Link: https://lore.kernel.org/r/3-v1-caa70ba3d1ab+1436e-ucmd_mask_jgg@nvidia.comSigned-off-by: Jason Gunthorpe <jgg@nvidia.com>