RDMA/rxe: Remove IB_SRQ_INIT_MASK

RDMA/rxe: Remove IB_SRQ_INIT_MASK

Currently the #define IB_SRQ_INIT_MASK is used to distinguish the
rxe_create_srq verb from the rxe_modify_srq verb so that some code can be
shared between these two subroutines.

This commit splits rxe_srq_chk_attr into two subroutines: rxe_srq_chk_init
and rxe_srq_chk_attr which handle the create_srq and modify_srq verbs
separately.

Link: https://lore.kernel.org/r/20220421014042.26985-2-rpearsonhpe@gmail.com
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>