RDMA/rtrs-clt: Use bitmask to check sess->flags

stable inclusion
from stable-5.10.21
commit 70123d9989df9571c07fd15491cd9ec09ec12180
bugzilla: 50609

--------------------------------

commit aaed465f upstream.

We may want to add new flags, so it's better to use bitmask to check flags.

Fixes: 6a98d71d ("RDMA/rtrs: client: main functionality")
Link: https://lore.kernel.org/r/20201217141915.56989-17-jinpu.wang@cloud.ionos.com


Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Gioh Kim <gi-oh.kim@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>