RDMA/ocrdma: Style and redundant code cleanup

Code cleanup and remove redundant code:

1) redundant initialization removed
2) braces changed as per CodingStyle.
3) redundant checks removed
4) extra braces in return statements removed.
5) removed unused pd pointer from mr.
6) reorganized get_dma_mr()
7) fixed set_av() to return error on invalid sgid index.
8) reference to ocrdma_dev removed from struct ocrdma_pd.

Signed-off-by: Naresh Gottumukkala <bgottumukkala@emulex.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>