[PATCH] distclean: Remove generated .dtb files

The patch 'arm/dt: Add dtb make rule' adds support to
create a .dtb file. But this is never removed afterwards.
Remove the generated .dtb file if 'distclean' is called.

Signed-off-by: Dirk Behme <redacted>
CC: Rob Herring <redacted>
CC: Shawn Guo <redacted>
CC: Jason Liu <redacted>
CC: Grant Likely <redacted>
---
 arch/arm/boot/Makefile |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/arm/boot/Makefile b/arch/arm/boot/Makefile
index 1cd9b0a..08f0d35 100644
--- a/arch/arm/boot/Makefile
+++ b/arch/arm/boot/Makefile

@@ -71,6 +71,8 @@ $(obj)/%.dtb: $(src)/dts/%.dts
 
 $(obj)/dtbs: $(addprefix $(obj)/, $(dtb-y))
 
+clean-files := *.dtb
+
 quiet_cmd_uimage = UIMAGE  $@
       cmd_uimage = $(CONFIG_SHELL) $(MKIMAGE) -A arm -O linux -T kernel \
 		   -C none -a $(LOADADDR) -e $(STARTADDR) \

-- 
1.7.0.4