platform/mellanox: fix potential race in mlxbf-tmfifo driver

This commit adds memory barrier for the 'vq' update in function
mlxbf_tmfifo_virtio_find_vqs() to avoid potential race due to
out-of-order memory write. It also adds barrier for the 'is_ready'
flag to make sure the initializations are visible before this flag
is checked.

Signed-off-by: Liming Sun <limings@nvidia.com>
Reviewed-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/b98c0ab61d644ba38fa9b3fd1607b138b0dd820b.1682518748.git.limings@nvidia.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>