[SCSI] u14-34f: fix scsi_dma_map failure case

When unsigned, scsi_dma_map may return -ENOMEM without triggering BUG_ON()
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/u14-34f.c

@@ -1111,7 +1111,8 @@ static int u14_34f_detect(struct scsi_host_template *tpnt) {
 
 static void map_dma(unsigned int i, unsigned int j) {
    unsigned int data_len = 0;
-   unsigned int k, count, pci_dir;
+   unsigned int k, pci_dir;
+   int count;
    struct scatterlist *sg;
    struct mscp *cpp;
    struct scsi_cmnd *SCpnt;