Report correct shader size.

Seems like this was an oversee in regards to adb089c816
It changed GLShader::ProgramCode to a std::vector, so sizeof is wrong.

src/video_core/renderer_opengl/gl_shader_cache.h

@@ -30,7 +30,7 @@ public:
 
     /// Gets the size of the shader in guest memory, required for cache management
     size_t GetSizeInBytes() const {
-        return sizeof(GLShader::ProgramCode);
+        return GLShader::MAX_PROGRAM_CODE_LENGTH * sizeof(u64);
     }
 
     /// Gets the shader entries for the shader