drm/xe/oa/uapi: Expose OA stream fd

The OA stream open perf op returns an fd with its own file_operations for
the newly initialized OA stream. These file_operations allow userspace to
enable or disable the stream, as well as apply a different metric
configuration for the OA stream. Userspace can also poll for data
availability. OA stream initialization is completed in this commit by
enabling the OA stream. When sampling is enabled this starts a hrtimer
which periodically checks for data availablility.

v2: Use stream properties for stream reconfiguration with
    DRM_XE_PERF_IOCTL_CONFIG
v3: Hold runtime_pm reference across oa buffer alloc/free
v4: Fix 32 bit build
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: José Roberto de Souza <jose.souza@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/20240618014609.3233427-9-ashutosh.dixit@intel.com

include/uapi/drm/xe_drm.h

@@ -1478,6 +1478,10 @@ enum drm_xe_oa_format_type {
  * @drm_xe_user_extension base.name set to @DRM_XE_OA_EXTENSION_SET_PROPERTY.
  * @param field in struct @drm_xe_perf_param points to the first
  * @drm_xe_ext_set_property struct.
+ *
+ * Exactly the same mechanism is also used for stream reconfiguration using
+ * the @DRM_XE_PERF_IOCTL_CONFIG perf fd ioctl, though only a subset of
+ * properties below can be specified for stream reconfiguration.
  */
 enum drm_xe_oa_property_id {
 #define DRM_XE_OA_EXTENSION_SET_PROPERTY	0