drm: Add macro to export functions only when CONFIG_DRM_DEBUG_SELFTEST is enabled

If we want to be able to write drmselftests for non-static core
functions that are not intended to be used by drivers we need this
functions to be exported.

This adds a macro that is tied of CONFIG_DRM_DEBUG_SELFTEST, and uses
that to export drm_internal_framebuffer_create, in order for
subsequent patches to be able to test it.

Reviewed-by: Daniel Vetter <[e-mail]>
Signed-off-by: Alexandru Gheorghe <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/drm_framebuffer.c

···
 
 	return fb;
 }
+EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_internal_framebuffer_create);
 
 /**
  * drm_mode_addfb2 - add an FB to the graphics configuration

include/drm/drmP.h

···
 	return true;
 }
 
+#if defined(CONFIG_DRM_DEBUG_SELFTEST_MODULE)
+#define EXPORT_SYMBOL_FOR_TESTS_ONLY(x) EXPORT_SYMBOL(x)
+#else
+#define EXPORT_SYMBOL_FOR_TESTS_ONLY(x)
+#endif
+
 #endif