 This is an important step to
remove the global state because it'll allow the programmer's data
to be used in delay functions.

Programmers that use internal delay can provide NULL as a context.

This is one of the steps on the way to move master's data
memory management behind the initialisation API, for more
context see other patches under the same topic specified below.

	if (!usecs)
		return;

	if (!programmer->delay)
		return internal_delay(flash, usecs); // maybe don't pass context into internal? or pass NULL?

	if (!flash) {
		msg_perr("%s called but flashctx is not valid!\n"
			 "Please report a bug at flashrom@flashrom.org\n", __func__);
		exit(1);
	}
	programmer->delay(flash, usecs);
}