bootfiles: Drop bbappend in favour of a newer upstream version

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>

meta-oniro-core/recipes-bsp/bootfiles/bootfiles.bbappend

-RPIFW_DATE = "20210914"
-SRCREV = "d5d14f484cec739901a088a58eed62452b6dadeb"
-RPIFW_SRC_URI = "https://github.com/raspberrypi/firmware/archive/${SRCREV}.tar.gz;downloadfilename=raspberrypi-firmware-${SRCREV}.tar.gz"
-RPIFW_S = "${WORKDIR}/firmware-${SRCREV}"
-
-SRC_URI = "${RPIFW_SRC_URI}"
-SRC_URI[sha256sum] = "f5b3d9fa60afbc103b00bc7f5899ea49ef61d353b88624b42dbf7669446a44ac"
-
-PV = "${RPIFW_DATE}"