idpf: implement get LAN MMIO memory regions

idpf: implement get LAN MMIO memory regions

The RDMA driver needs to map its own MMIO regions for the sake of
performance, meaning the IDPF needs to avoid mapping portions of the BAR
space. However, to be HW agnostic, the IDPF cannot assume where
these are and must avoid mapping hard coded regions as much as possible.

The IDPF maps the bare minimum to load and communicate with the
control plane, i.e., the mailbox registers and the reset state
registers. Because of how and when mailbox register offsets are
initialized, it is easier to adjust the existing defines to be relative
to the mailbox region starting address. Use a specific mailbox register
write function that uses these relative offsets. The reset state
register addresses are calculated the same way as for other registers,
described below.

The IDPF then calls a new virtchnl op to fetch a list of MMIO regions
that it should map. The addresses for the registers in these regions are
calculated by determining what region the register resides in, adjusting
the offset to be relative to that region, and then adding the
register's offset to that region's mapped address.

If the new virtchnl op is not supported, the IDPF will fallback to
mapping the whole bar. However, it will still map them as separate
regions outside the mailbox and reset state registers. This way we can
use the same logic in both cases to access the MMIO space.

Reviewed-by: Madhu Chittim <madhu.chittim@intel.com>
Signed-off-by: Joshua Hay <joshua.a.hay@intel.com>
Signed-off-by: Tatyana Nikolova <tatyana.e.nikolova@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>