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/qemu.mk b/qemu.mk
index b78a1ed..4995161 100644
--- a/qemu.mk
+++ b/qemu.mk
@@ -24,7 +24,7 @@
 # Targets
 ################################################################################
 all: bios-qemu qemu soc-term
-all-clean: bios-qemu-clean busybox-clean linux-clean optee-os-clean \
+clean: bios-qemu-clean busybox-clean linux-clean optee-os-clean \
 	optee-client-clean qemu-clean soc-term-clean check-clean
 
 -include toolchain.mk