IB/{core,hw}: Have ib_umem_get extract the ib_ucontext from ib_udata

ib_umem_get() can only be called in a method callback, which always has a
udata parameter. This allows ib_umem_get() to derive the ucontext pointer
directly from the udata without requiring the drivers to find it in some
way or another.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>

drivers/infiniband/hw/cxgb3/iwch_provider.c

@@ -540,7 +540,7 @@ static struct ib_mr *iwch_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
 
 	mhp->rhp = rhp;
 
-	mhp->umem = ib_umem_get(pd->uobject->context, start, length, acc, 0);
+	mhp->umem = ib_umem_get(udata, start, length, acc, 0);
 	if (IS_ERR(mhp->umem)) {
 		err = PTR_ERR(mhp->umem);
 		kfree(mhp);