RDMA/bnxt_re: fix or'ing of data into an uninitialized struct member

The struct member comp_mask has not been initialized however a bit
pattern is being bitwise or'd into the member and hence other bit
fields in comp_mask may contain any garbage from the stack. Fix this
by making the bitwise or into an assignment.

Fixes: 95b86d1c

 ("RDMA/bnxt_re: Update kernel user abi to pass chip context")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>