Blackfin: kgdb_test: rework code to avoid -O0 usage

__kfree_rcu() in rcupdate.h bugs when parameter offset is not a constant
at compile time.  Since we build the kgdb_test module with -O0 and it
includes this header file, we hit the bug.  So drop the -O0 and mark the
one func we need for the test as noinline (so we can set a breakpoint on
it and have it be hit).

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/kernel/Makefile b/arch/blackfin/kernel/Makefile
index b7bdc42..1f88edd 100644
--- a/arch/blackfin/kernel/Makefile
+++ b/arch/blackfin/kernel/Makefile
@@ -38,6 +38,6 @@
 
 # the kgdb test puts code into L2 and without linker
 # relaxation, we need to force long calls to/from it
-CFLAGS_kgdb_test.o := -mlong-calls -O0
+CFLAGS_kgdb_test.o := -mlong-calls
 
 obj-$(CONFIG_DEBUG_MMRS)             += debug-mmrs.o