serial: Support OXPCIe952 aka Oxford Semiconductor Ltd Device c138 (1415:c138)

serial: Support OXPCIe952 aka Oxford Semiconductor Ltd Device c138 (1415:c138)

Because they are PCIe and machine nowadys have those instead of
PCI, and they are inexpensive.

Tested with 1415:c138. Should also work on 0xc11f, 0xc11b models
of that chip.

Also on  OXPCIe200 1 Native UART 1415: 0xc40b, 0xc40f, 0xc41b,
0xc41f, 0xc42b, 0xc42f, 0xc43b, 0xc43f, 0xc44b, 0xc44f, 0xc45b
0xc45f, 0xc46b, 0xc46f, 0xc47b, 0xc47f, 0xc48b, 0xc48f, 0xc49b
0xc49f, 0xc4ab, 0xc4af, 0xc4bb, 0xc4bf, 0xc4cb, 0xc4cf

but since I don't have any of those cards this patch does not
enable it.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v1: Init for ARM and add offset to virt addr]
[v2: Remove the offset usage]
Tested-by: Aravind Gopalakrishnan <aravind.gopalakrishnan@amd.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>