[media] Add missing help for some menuconfig items

Help was missing during some items reorganization. Add them.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/parport/Kconfig

 menuconfig MEDIA_PARPORT_SUPPORT
-	bool "V4L ISA and parallel port devices"
+	bool "ISA and parallel port devices"
 	depends on (ISA || PARPORT) && MEDIA_CAMERA_SUPPORT
+	help
+	  Enables drivers for ISA and parallel port bus. If you
+	  need media drivers using those legacy buses, say Y.
 
 if MEDIA_PARPORT_SUPPORT
 config VIDEO_BWQCAM

drivers/media/pci/Kconfig

 menuconfig MEDIA_PCI_SUPPORT
 	bool "Media PCI Adapters"
 	depends on PCI && MEDIA_SUPPORT
+	help
+	  Enable media drivers for PCI/PCIe bus.
+	  If you have such devices, say Y.
 
 if MEDIA_PCI_SUPPORT
 

drivers/media/usb/Kconfig

 menuconfig MEDIA_USB_SUPPORT
 	bool "Media USB Adapters"
 	depends on USB && MEDIA_SUPPORT
+	help
+	  Enable media drivers for USB bus.
+	  If you have such devices, say Y.
 
 if MEDIA_USB_SUPPORT