kbuild: fix unneeded rebuilds in drivers/media/video after moving source tree

This fixes some uneeded rebuilds under drivers/media/video after moving
the source tree. The makefiles used $(src) and $(srctree) for include
paths, which is unnecessary. Changed to use relative paths.

Compile tested, produces byte-identical code to the previous makefiles.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index 4092a5e..b3ea2d6 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -84,4 +84,4 @@
 obj-$(CONFIG_USB_KONICAWC)      += usbvideo/
 obj-$(CONFIG_USB_VICAM)         += usbvideo/
 
-EXTRA_CFLAGS += -I$(srctree)/drivers/media/dvb/dvb-core
+EXTRA_CFLAGS += -Idrivers/media/dvb/dvb-core