treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

drivers/ps3/ps3av.c

@@ -769,7 +769,7 @@ static int ps3av_auto_videomode(struct ps3av_pkt_av_get_hw_conf *av_hw_conf)
 		switch (info->monitor_type) {
 		case PS3AV_MONITOR_TYPE_DVI:
 			dvi = PS3AV_MODE_DVI;
-			/* fall through */
+			fallthrough;
 		case PS3AV_MONITOR_TYPE_HDMI:
 			id = ps3av_hdmi_get_id(info);
 			break;

drivers/ps3/ps3av_cmd.c

@@ -693,11 +693,11 @@ void ps3av_cmd_set_audio_mode(struct ps3av_pkt_audio_mode *audio, u32 avport,
 	switch (ch) {
 	case PS3AV_CMD_AUDIO_NUM_OF_CH_8:
 		audio->audio_enable[3] = 1;
-		/* fall through */
+		fallthrough;
 	case PS3AV_CMD_AUDIO_NUM_OF_CH_6:
 		audio->audio_enable[2] = 1;
 		audio->audio_enable[1] = 1;
-		/* fall through */
+		fallthrough;
 	case PS3AV_CMD_AUDIO_NUM_OF_CH_2:
 	default:
 		audio->audio_enable[0] = 1;