net: hns3: add handling of hw errors reported through MSIX

This patch adds handling for HNS3 hardware errors(non-standard)
which are reported through MSIX interrupts and not through
PCIe AER channel.

These MSIX reported hardware errors are handled using common
misc. interrupt handler. Hardware error related registers
cannot be cleared in context to the interrupt received as
they require *heavy* access to hardware using IMP(Integrated
Mangement Processor) commands. Hence, we defer the clearing
of such error events till later time.

Since, we have defered exact identification of errors we
will have to defer the level of receovery/reset which
might be required. Hence, a new reset type UNKNOWN reset
has been introduced which effectively defers the assertion
of the reset till we get hold of kind of errors at later
time.

Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>