media: media/radio/Kconfig: add back RADIO_ISA

Patch 258c524b inadvertently removed the 'select RADIO_ISA' line for
the RADIO_RTRACK.

Fixes: 258c524b ("radio: allow building ISA drivers with COMPILE_TEST")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/radio/Kconfig

@@ -257,6 +257,7 @@ config RADIO_RTRACK
 	tristate "AIMSlab RadioTrack (aka RadioReveal) support"
 	depends on ISA || COMPILE_TEST
 	depends on VIDEO_V4L2
+	select RADIO_ISA
 	---help---
 	  Choose Y here if you have one of these FM radio cards, and then fill
 	  in the port address below.