staging: rdma: hfi1: Remove casts of pointer to same type

Casting a pointer to a pointer of the same type is unnecessary, so
remove these unnecessary casts.

This was done with Coccinelle:

@@
type T;
T *ptr;
@@
- (T *)ptr
+ ptr

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>