drm/mipi-dsi: use correct return type for the DSC functions

The functions mipi_dsi_compression_mode() and
mipi_dsi_picture_parameter_set() return 0-or-error rather than a buffer
size. Follow example of other similar MIPI DSI functions and use int
return type instead of size_t.

Fixes: f4dea1aaa9a1 ("drm/dsi: add helpers for DSI compression mode and PPS packets")
Reviewed-by: Marijn Suijten <[e-mail]>
Reviewed-by: Jessica Zhang <[e-mail]>
Signed-off-by: Dmitry Baryshkov <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/drm_mipi_dsi.c

···
  *
  * Return: 0 on success or a negative error code on failure.
  */
-ssize_t mipi_dsi_compression_mode(struct mipi_dsi_device *dsi, bool enable)
+int mipi_dsi_compression_mode(struct mipi_dsi_device *dsi, bool enable)
 {
 	/* Note: Needs updating for non-default PPS or algorithm */
 	u8 tx[2] = { enable << 0, 0 };
···
  *
  * Return: 0 on success or a negative error code on failure.
  */
-ssize_t mipi_dsi_picture_parameter_set(struct mipi_dsi_device *dsi,
-				       const struct drm_dsc_picture_parameter_set *pps)
+int mipi_dsi_picture_parameter_set(struct mipi_dsi_device *dsi,
+				   const struct drm_dsc_picture_parameter_set *pps)
 {
 	struct mipi_dsi_msg msg = {
 		.channel = dsi->channel,

include/drm/drm_mipi_dsi.h

···
 int mipi_dsi_turn_on_peripheral(struct mipi_dsi_device *dsi);
 int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi,
 					    u16 value);
-ssize_t mipi_dsi_compression_mode(struct mipi_dsi_device *dsi, bool enable);
-ssize_t mipi_dsi_picture_parameter_set(struct mipi_dsi_device *dsi,
-				       const struct drm_dsc_picture_parameter_set *pps);
+int mipi_dsi_compression_mode(struct mipi_dsi_device *dsi, bool enable);
+int mipi_dsi_picture_parameter_set(struct mipi_dsi_device *dsi,
+				   const struct drm_dsc_picture_parameter_set *pps);
 
 ssize_t mipi_dsi_generic_write(struct mipi_dsi_device *dsi, const void *payload,
 			       size_t size);