avfilter/gblur_vulkan: fix memory leak

Whether failed or not, the block of codes labeled with fail should
be always run to ensure the av_free(kernel_def) is executed.

Signed-off-by: Wu Jianhua <jianhua.wu@intel.com>

libavfilter/vf_gblur_vulkan.c

@@ -296,8 +296,6 @@ static av_cold int init_filter(AVFilterContext *ctx, AVFrame *in)
 
     s->initialized = 1;
 
-    return 0;
-
 fail:
     av_free(kernel_def);
     return err;