RDMA: Remove uverbs_ex_cmd_mask values that are linked to functions

Since a while now the uverbs layer checks if the driver implements a
function before allowing the ucmd to proceed. This largely obsoletes the
cmd_mask stuff, but there is some tricky bits in drivers preventing it
from being removed.

Remove the easy elements of uverbs_ex_cmd_mask by pre-setting them in the
core code. These are triggered soley based on the related ops function
pointer.

query_device_ex is not triggered based on an op, but all drivers already
implement something compatible with the extension, so enable it globally
too.

Link: https://lore.kernel.org/r/2-v1-caa70ba3d1ab+1436e-ucmd_mask_jgg@nvidia.com


Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>