Remove 300ms delay before logoless boot

[Fordi]

Tested on hardware, removing the delay clears up the boot noise problem in issue #9

[Fordi]

This PR eliminates all pre-boot screen noise for games with disable_startup_logo.

Findings:

Removing the delay mostly resolves it on hardware - though there's still a nigh-imperceptible one-frame flash of randomness..

I'm a little confused: Hoisting the pen(0, 0, 0); clear(); out of the #ifdef NO_STARTUP_LOGO (so it hits both branches) does not resolve the issue, even though it should, in theory.

Moving the backlight(75); into its own #ifdef NO_STARTUP_LOGO branch after the sleep(300);, also mostly resolves it, though with the same one-frame flash.

I was not able to get rid of the flash despite experimentation, and this is the simplest change that (mostly) succeeded, so I'm pulling this PR out of draft.

The missing piece was to flip the screen buffer in the NO_STARTUP_LOGO branch, then wait for the transfer to finish and vsync to settle out before flipping on the backlight.

[Fordi]

Pulling back to draft; I think what's going on is that the screen buffers aren't getting initialized.

[Fordi]

Ok. Clearing the screen and flipping twice did it, but only after making it wait for the flips.

[Fordi]

I keep pulling back to draft, but it occurs to me there might be An Easier Way™.

[Fordi]

Final one.

Incidentally, the program used for testing is just:

#include "picosystem.hpp"
using namespace picosystem;

void init() {
    // Whatever's on screen stays on screen for a second
    sleep(1000);
    // Called once at the start, this is an ideal place to do any setup for your project.
}

void update(uint32_t tick) {
    // Called at a fixed rate - by default every 10ms. Perform any tasks that update the
    // game world state. Because it is called at a fixed rate you can easily time movement
    //  and events. tick is the number of update() calls since the game started.
}


void draw() {
    // Called as often as possible, aiming for 60 fps
}

[Fordi]

An empty initializer initializes to 0's. No initializer leaves it randomized.

[Fordi]

Just one leaves The Flash™, two leaves it out.

[Gadgetoid]

So it does! We'll probably dig deeper into this. Thank you!

[Gadgetoid]

Thank you!