V4L/DVB: mantis: Fix IR_CORE dependency

This build bug triggers:

 drivers/built-in.o: In function `mantis_exit':
 (.text+0x377413): undefined reference to `ir_input_unregister'
 drivers/built-in.o: In function `mantis_input_init':
 (.text+0x3774ff): undefined reference to `__ir_input_register'

If MANTIS_CORE is enabled but IR_CORE is not. Add the correct
dependency.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/media/dvb/mantis/Kconfig

 config MANTIS_CORE
 	tristate "Mantis/Hopper PCI bridge based devices"
-	depends on PCI && I2C && INPUT
+	depends on PCI && I2C && INPUT && IR_CORE
 
 	help
 	  Support for PCI cards based on the Mantis and Hopper PCi bridge.