RDMA/uverbs: Fix kernel-doc warning of _uverbs_alloc

Fix the following W=1 compilation warning:

drivers/infiniband/core/uverbs_ioctl.c:108: warning: expecting prototype for uverbs_alloc(). Prototype was for _uverbs_alloc() instead

Fixes: 461bb2ee ("IB/uverbs: Add a simple allocator to uverbs_attr_bundle")
Link: https://lore.kernel.org/r/20210302074214.1054299-3-leon@kernel.org


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