uverbs was blocking srq_types the driver doesn't support based on the
CREATE_XSRQ cmd_mask. Fix all drivers to check for supported srq_types
during create_srq and move CREATE_XSRQ to the core code.

Link: https://lore.kernel.org/r/5-v1-caa70ba3d1ab+1436e-ucmd_mask_jgg@nvidia.comSigned-off-by: Jason Gunthorpe <jgg@nvidia.com>