drm/i915: Increase FLR timeout from 3s to 9s

Following the guidelines it takes 3 seconds to perform an FLR
reset. Let's give it a bit more slack because this time can
change depending on the platform and on the firmware

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240523235853.171796-1-andi.shyti@linux.intel.com