RDMA/iwpm: Remove not-needed reference counting

iwpm_init() and iwpm_exit() are called only once during iw_cm module
load. This makes whole reference count implementation not needed at all.

Link: https://lore.kernel.org/r/1778ded873ba58c9fadc5bb25038de1cec843bec.1627048781.git.leonro@nvidia.com


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