spinner: Don't specify EGL_COLOR_BUFFER_TYPE EGL attribute
Specifying EGL_COLOR_BUFFER_TYPE seems to confuse the ubuntu-touch
emulator EGL implementation, causing it to not find any matching
EGLConfigs. This seems like a bug in the EGL implementation.
In any case, setting this attribute to EGL_RGB_BUFFER is not actually
needed since that's the default value.
Approved by Alberto Aguirre, PS Jenkins bot.