RDMA/rxe: Set default vendor ID

The RXE driver doesn't set vendor_id and user space applications see
zeros. This causes to pyverbs tests to fail with the following traceback,
because the expectation is to have valid vendor_id.

Traceback (most recent call last):
  File "tests/test_device.py", line 51, in test_query_device
    self.verify_device_attr(attr)
  File "tests/test_device.py", line 77, in verify_device_attr
    assert attr.vendor_id != 0

In order to fix it, we will set vendor_id 0XFFFFFF, according to the IBTA
v1.4 A3.3.1 VENDOR INFORMATION section.

"""
A vendor that produces a generic controller (i.e., one that supports a
standard I/O protocol such as SRP), which does not have vendor specific
device drivers, may use the value of 0xFFFFFF in the VendorID field.
"""

Before:

hca_id: rxe0
        transport:                      InfiniBand (0)
        fw_ver:                         0.0.0
        node_guid:                      5054:00ff:feaa:5363
        sys_image_guid:                 5054:00ff:feaa:5363
        vendor_id:                      0x0000

After:

hca_id: rxe0
        transport:                      InfiniBand (0)
        fw_ver:                         0.0.0
        node_guid:                      5054:00ff:feaa:5363
        sys_image_guid:                 5054:00ff:feaa:5363
        vendor_id:                      0xffffff

Fixes: 8700e3e7 ("Soft RoCE driver")
Link: https://lore.kernel.org/r/20200406173501.1466273-1-leon@kernel.org


Signed-off-by: Zhu Yanjun <yanjunz@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>