scsi: fix compiler warning with DEBUG and 48bit LBAs

Commit 2b42c931 ("ahci: support LBA48 data reads for 2+TB drives")
introduced conditional code which triggers a warning when compiled
with DEBUG enabled:

In file included from common/cmd_scsi.c:12:0:
common/cmd_scsi.c: In function 'scsi_read':
include/common.h:109:4: warning: 'smallblks' may be used uninitialized in this function [-Wmaybe-uninitialized]
...

Since this is for debug only, take the easy way and initialize the
variable explicitly on declaration to avoid the warning.
(Fix a nearby whitespace error on the way.)

Tested-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Andre Przywara <osp@andrep.de>

common/cmd_scsi.c

@@ -368,7 +368,7 @@ static ulong scsi_read(int device, lbaint_t blknr, lbaint_t blkcnt,
 {
 	lbaint_t start, blks;
 	uintptr_t buf_addr;
-	unsigned short smallblks;
+	unsigned short smallblks = 0;
 	ccb* pccb=(ccb *)&tempccb;
 	device&=0xff;
 	/* Setup  device
@@ -391,7 +391,7 @@ static ulong scsi_read(int device, lbaint_t blknr, lbaint_t blkcnt,
 			scsi_setup_read16(pccb, start, blocks);
 			start += blocks;
 			blks -= blocks;
-		} else 
+		} else
 #endif
 		if (blks > SCSI_MAX_READ_BLK) {
 			pccb->datalen=scsi_dev_desc[device].blksz * SCSI_MAX_READ_BLK;