xen/blkback: Remove the unused typedefs.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/block/xen-blkback/common.h

@@ -76,8 +76,6 @@ struct blkif_x86_32_response {
 	uint8_t         operation;       /* copied from request */
 	int16_t         status;          /* BLKIF_RSP_???       */
 };
-typedef struct blkif_x86_32_request blkif_x86_32_request_t;
-typedef struct blkif_x86_32_response blkif_x86_32_response_t;
 #pragma pack(pop)
 
 /* x86_64 protocol version */
@@ -94,8 +92,6 @@ struct blkif_x86_64_response {
 	uint8_t         operation;       /* copied from request */
 	int16_t         status;          /* BLKIF_RSP_???       */
 };
-typedef struct blkif_x86_64_request blkif_x86_64_request_t;
-typedef struct blkif_x86_64_response blkif_x86_64_response_t;
 
 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
 		  struct blkif_common_response);