hexagon: suppress error message for 'make clean'

'make ARCH=hexagon clean' emits an error message as follows:

  $ make ARCH=hexagon clean
  gcc: error: unrecognized command line option '-G0'

You can suppress it by setting the correct CROSS_COMPILE=,
but we should not require any compiler for cleaning.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Acked-by: NBrian Cain <bcain@codeaurora.org>

arch/hexagon/Makefile

@@ -30,7 +30,7 @@ TIR_NAME := r19
 KBUILD_CFLAGS += -ffixed-$(TIR_NAME) -DTHREADINFO_REG=$(TIR_NAME) -D__linux__
 KBUILD_AFLAGS += -DTHREADINFO_REG=$(TIR_NAME)
 
-LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name)
+LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name 2>/dev/null)
 libs-y += $(LIBGCC)
 
 head-y := arch/hexagon/kernel/head.o