drm/xe/oa: OA stream initialization (OAG)

Implement majority of OA stream initialization (as part of OA stream open)
ioctl). OAG buffer is allocated for receiving perf counter samples from
HW. OAG unit is initialized and the selected OA metric configuration is
programmed into OAG unit HW using a command/batch buffer.

Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240618014609.3233427-8-ashutosh.dixit@intel.com