sfc: support VI strides other than 8k

sfc: support VI strides other than 8k

BugLink: https://bugs.launchpad.net/bugs/1836635
Medford2 can also have 16k or 64k VI stride.  This is reported by MCDI in
 GET_CAPABILITIES, which fortunately is called before the driver does
 anything sensitive to the VI stride (such as accessing or even allocating
 VIs past the zeroth).

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 71827443017789da691b402090c6be6138f43157)
Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>