scsi: ultrastor.c depends on ISA_DMA_API

Fix build when CONFIG_ISA_DMA_API is not enabled. Fixes these build
errors (on x86_64):

../drivers/scsi/ultrastor.c: In function 'ultrastor_14f_detect':
../drivers/scsi/ultrastor.c:519:5: error: implicit declaration of function 'request_dma' [-Werror=implicit-function-declaration]
     if (config.dma_channel && request_dma(config.dma_channel,"Ultrastor")) {
     ^
../drivers/scsi/ultrastor.c: In function 'ultrastor_release':
../drivers/scsi/ultrastor.c:658:3: error: implicit declaration of function 'free_dma' [-Werror=implicit-function-declaration]
   free_dma(shost->dma_channel);
   ^
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/Kconfig

@@ -1433,7 +1433,7 @@ config SCSI_U14_34F_MAX_TAGS
 
 config SCSI_ULTRASTOR
 	tristate "UltraStor SCSI support"
-	depends on X86 && ISA && SCSI
+	depends on X86 && ISA && SCSI && ISA_DMA_API
 	---help---
 	  This is support for the UltraStor 14F, 24F and 34F SCSI-2 host
 	  adapter family.  This driver is explained in section 3.12 of the