RDMA/hns: Modify the mapping attribute of doorbell to device

RDMA/hns: Modify the mapping attribute of doorbell to device

BugLink: https://bugs.launchpad.net/bugs/1959376
commit 39d5534b1302189c809e90641ffae8cbdc42a8fc upstream.

It is more general for ARM device drivers to use the device attribute to
map PCI BAR spaces.

Fixes: 9a4435375cd1 ("IB/hns: Add driver files for hns RoCE driver")
Link: https://lore.kernel.org/r/20211206133652.27476-1-liangwenpeng@huawei.com
Signed-off-by: Yixing Liu <liuyixing1@huawei.com>
Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>