drm/i915/guc: Fix Gen9 GuC loading workarounds

In commit 4502e9ec

 ("drm/i915/uc: Unify firmware loading") we
stopped converting errors detected during firmware transfer into
-EAGAIN and this indirectly killed our workarounds for Gen9 GuC.
Reactivate those workarounds by looking for actual -ETIMEDOUT error.

Testcase: igt@drv_selftest@live_hangcheck
Reported-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
References: commit 4502e9ec

 ("drm/i915/uc: Unify firmware loading")

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20181016085931.23532-1-michal.wajdeczko@intel.com