hisi_acc_vfio_pci: update function return values.

hisi_acc_vfio_pci: update function return values.

In this driver file, many functions call sub-functions and use ret
to store the error code of the sub-functions.
However, instead of directly returning ret to the caller, they use a
converted error code, which prevents the end-user from clearly
understanding the root cause of the error.
Therefore, the code needs to be modified to directly return the error
code from the sub-functions.

Signed-off-by: Longfang Liu <liulongfang@huawei.com>
Reviewed-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Link: https://lore.kernel.org/r/20250510081155.55840-7-liulongfang@huawei.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>