RDMA/rxe: Add check for supported QP types

Current rdma_rxe only supports five QP types, attempting to create any
others should return an error - the type check was missed.

Link: https://lore.kernel.org/r/20201216071755.149449-2-yangx.jy@cn.fujitsu.com


Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>