scsi_dh: force modular build if SCSI is a module

When the scsi_dh core was moved into the scsi core module,
CONFIG_SCSI_DH became a 'bool' option, and now anything depending on it
can be built-in even when CONFIG_SCSI=m. This of course cannot link
successfully:

drivers/scsi/built-in.o: In function `rdac_init':
scsi_dh_alua.c:(.init.text+0x14): undefined reference to `scsi_register_device_handler'
scsi_dh_alua.c:(.init.text+0x64): undefined reference to `scsi_unregister_device_handler'
drivers/scsi/built-in.o: In function `alua_init':
scsi_dh_alua.c:(.init.text+0xb0): undefined reference to `scsi_register_device_handler'

As a workaround, this adds an extra dependency on CONFIG_SCSI, so
Kconfig can figure out whether built-in is allowed or not.

Signed-off-by: Arnd Bergmann <[e-mail]>
Fixes: 086b91d052eb ("scsi_dh: integrate into the core SCSI code")
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/device_handler/Kconfig

···
 
 config SCSI_DH_RDAC
 	tristate "LSI RDAC Device Handler"
-	depends on SCSI_DH
+	depends on SCSI_DH && SCSI
 	help
 	If you have a LSI RDAC select y. Otherwise, say N.
 
 config SCSI_DH_HP_SW
 	tristate "HP/COMPAQ MSA Device Handler"
-	depends on SCSI_DH
+	depends on SCSI_DH && SCSI
 	help
 	If you have a HP/COMPAQ MSA device that requires START_STOP to
 	be sent to start it and cannot upgrade the firmware then select y.
···
 
 config SCSI_DH_EMC
 	tristate "EMC CLARiiON Device Handler"
-	depends on SCSI_DH
+	depends on SCSI_DH && SCSI
 	help
 	If you have a EMC CLARiiON select y. Otherwise, say N.
 
 config SCSI_DH_ALUA
 	tristate "SPC-3 ALUA Device Handler"
-	depends on SCSI_DH
+	depends on SCSI_DH && SCSI
 	help
 	  SCSI Device handler for generic SPC-3 Asymmetric Logical Unit
 	  Access (ALUA).