drm/i915/gt: Flush to global observation point before breadcrumb write

drm/i915/gt: Flush to global observation point before breadcrumb write

Add flag to pipecontrol instruction to ensure in-flight writes are
flushed to global observation point. Also split the pipecontrol
instruction like we have in gen8.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/5886
Signed-off-by: Prathap Kumar Valsan <prathap.kumar.valsan@intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220927171313.6553-1-nirmoy.das@intel.com