scsi: target/core: Use the SECTOR_SHIFT constant

Instead of duplicating the SECTOR_SHIFT definition from <linux/blkdev.h>,
use it. This patch does not change any functionality.

Reviewed-by: Christoph Hellwig <[e-mail]>
Cc: Nicholas Bellinger <[e-mail]>
Cc: Mike Christie <[e-mail]>
Cc: Hannes Reinecke <[e-mail]>
Signed-off-by: Bart Van Assche <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/target/target_core_iblock.c

···
 		}
 
 		/* Always in 512 byte units for Linux/Block */
-		block_lba += sg->length >> IBLOCK_LBA_SHIFT;
+		block_lba += sg->length >> SECTOR_SHIFT;
 		sectors -= 1;
 	}
 
···
 		}
 
 		/* Always in 512 byte units for Linux/Block */
-		block_lba += sg->length >> IBLOCK_LBA_SHIFT;
+		block_lba += sg->length >> SECTOR_SHIFT;
 		sg_num--;
 	}
 

drivers/target/target_core_iblock.h

···
 #define IBLOCK_VERSION		"4.0"
 
 #define IBLOCK_MAX_CDBS		16
-#define IBLOCK_LBA_SHIFT	9
 
 struct iblock_req {
 	refcount_t pending;