sdcard_image-rpi.bbclass: Fix when RPI_SDIMG_EXTRA_DEPENDS not defined
If the variable is not defined, bitbake will fail:
[...]
Task 'depends' should be specified in the form 'packagename:task'
[...]
This is because not expanding the variable leaves an invalid entry.
@@ -49,6 +49,8 @@ SDIMG_ROOTFS = "${IMGDEPLOYDIR}/${IMAGE_LINK_NAME}.${SDIMG_ROOTFS_TYPE}"
# For the names of kernel artifacts
inherit kernel-artifact-names
+RPI_SDIMG_EXTRA_DEPENDS ?= ""
+
do_image_rpi_sdimg[depends] = " \
parted-native:do_populate_sysroot \
mtools-native:do_populate_sysroot \
