drm/xe/guc: Resend potentially lost H2G MMIO request

drm/xe/guc: Resend potentially lost H2G MMIO request

There could be a scenario where the VF driver is resuming faster
than the driver PF is able to complete the VF FLR sequence which
includes reset of the VF scratch registers.  This may result in
deletion of the ongoing HXG message (it could be either a host
request or a GuC response).

When we detect that HXG message was likey lost (scratch register
with HXG header was zeroed) try to send this request once more
before giving up.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
Reviewed-by: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
Link: https://lore.kernel.org/r/20250528090021.329-1-michal.wajdeczko@intel.com