Replace 'all-clean' targets with 'clean'

Signed-off-by: Victor Chong <victor.chong@linaro.org>
Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
diff --git a/rpi3.mk b/rpi3.mk
index 94b0956..4cfb403 100644
--- a/rpi3.mk
+++ b/rpi3.mk
@@ -59,7 +59,7 @@
 ################################################################################
 all: rpi3-firmware arm-tf optee-os optee-client xtest u-boot u-boot-jtag-bin\
 	linux update_rootfs
-all-clean: arm-tf-clean busybox-clean u-boot-clean u-boot-jtag-bin-clean \
+clean: arm-tf-clean busybox-clean u-boot-clean u-boot-jtag-bin-clean \
 	optee-os-clean optee-client-clean rpi3-firmware-clean head-bin-clean
 
 -include toolchain.mk