kunit: include debugfs header file

An extra #include statement is needed to ensure the prototypes for debugfs
interfaces are visible, avoiding this warning:

lib/kunit/debugfs.c:28:6: error: no previous prototype for 'kunit_debugfs_cleanup' [-Werror=missing-prototypes]
lib/kunit/debugfs.c:33:6: error: no previous prototype for 'kunit_debugfs_init' [-Werror=missing-prototypes]
lib/kunit/debugfs.c:102:6: error: no previous prototype for 'kunit_debugfs_create_suite' [-Werror=missing-prototypes]
lib/kunit/debugfs.c:118:6: error: no previous prototype for 'kunit_debugfs_destroy_suite' [-Werror=missing-prototypes]

Link: https://lkml.kernel.org/r/20230517131102.934196-10-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Gow <davidgow@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/kunit/debugfs.c

@@ -10,6 +10,7 @@
 #include <kunit/test.h>
 
 #include "string-stream.h"
+#include "debugfs.h"
 
 #define KUNIT_DEBUGFS_ROOT             "kunit"
 #define KUNIT_DEBUGFS_RESULTS          "results"