Blackfin arch: Add in cflag to support mlong-calls for kgdb_test

Signed-off-by: NGrace Pan <grace.pan@analog.com>
Signed-off-by: NBryan Wu <cooloney@kernel.org>

arch/blackfin/kernel/Makefile

@@ -15,6 +15,8 @@ else
     obj-y += time.o
 endif
 
+CFLAGS_kgdb_test.o := -mlong-calls -O0
+
 obj-$(CONFIG_IPIPE)                  += ipipe.o
 obj-$(CONFIG_IPIPE_TRACE_MCOUNT)     += mcount.o
 obj-$(CONFIG_BFIN_GPTIMERS)          += gptimers.o