media: rcar_jpu: fix two kernel-doc markups

On kernel-doc, struct declarations should be declared as "struct foo".

Fix the following warnings:
	drivers/media/platform/rcar_jpu.c:265: warning: cannot understand function prototype: 'struct jpu_q_data '
	drivers/media/platform/rcar_jpu.c:281: warning: cannot understand function prototype: 'struct jpu_ctx '
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/rcar_jpu.c

@@ -257,7 +257,7 @@ struct jpu_fmt {
 };
 
 /**
- * jpu_q_data - parameters of one queue
+ * struct jpu_q_data - parameters of one queue
  * @fmtinfo: driver-specific format of this queue
  * @format: multiplanar format of this queue
  * @sequence: sequence number
@@ -269,7 +269,7 @@ struct jpu_q_data {
 };
 
 /**
- * jpu_ctx - the device context data
+ * struct jpu_ctx - the device context data
  * @jpu: JPEG IP device for this context
  * @encoder: compression (encode) operation or decompression (decode)
  * @compr_quality: destination image quality in compression (encode) mode