linux-raspberrypi: Drop unnecessary code

* The kerneltype variable is not used anywhere after being set.

* The manipulation of KERNEL_DEVICETREE is effectively a no-op, we read the
  current value in get_dts() and store this back into the same variable.

Signed-off-by: Paul Barker <pbarker@toganlabs.com>

classes/linux-raspberrypi-base.bbclass

@@ -1,24 +1,7 @@
 inherit linux-kernel-base
 
-def get_dts(d, ver=None):
-    import re
-
-    staging_dir = d.getVar("STAGING_KERNEL_BUILDDIR")
-    dts = d.getVar("KERNEL_DEVICETREE")
-
-    # d.getVar() might return 'None' as a normal string
-    # leading to 'is None' check isn't enough.
-    # TODO: Investigate if this is a bug in bitbake
-    if ver is None or ver == "None":
-        ''' if 'ver' isn't set try to grab the kernel version
-        from the kernel staging '''
-        ver = get_kernelversion_file(staging_dir)
-
-    return dts
-
-
 def split_overlays(d, out, ver=None):
-    dts = get_dts(d, ver)
+    dts = d.getVar("KERNEL_DEVICETREE")
     if out:
         overlays = oe.utils.str_filter_out('\S+\-overlay\.dtb$', dts, d)
         overlays = oe.utils.str_filter_out('\S+\.dtbo$', overlays, d)

classes/sdcard_image-rpi.bbclass

@@ -86,7 +86,7 @@ IMAGE_CMD_rpi-sdimg () {
 	echo "Creating filesystem with Boot partition ${BOOT_SPACE_ALIGNED} KiB and RootFS $ROOTFS_SIZE KiB"
 
 	# Check if we are building with device tree support
-	DTS="${@get_dts(d)}"
+	DTS="${KERNEL_DEVICETREE}"
 
 	# Initialize sdcard image file
 	dd if=/dev/zero of=${SDIMG} bs=1024 count=0 seek=${SDIMG_SIZE}