Attach the process and thread when calling platform_tls_get_check() the first time too

Similar as to what is done in platform_tls_get() already. This
fixes heap corruption when calling eglGetDisplay() before
any function calling platform_tls_get() is called (in the
same process or thread).

https://github.com/raspberrypi/firmware/issues/112
https://github.com/raspberrypi/firmware/issues/99