Fix shift + play midi data for ddj-flx4 controller mapping

[Aquassaut]

Hi,

After the issue #13813 and the resolving PR #13815, I found another controller mapping issue for the DDJ-flx4, whereby the mapping expects midino 0x47 for shift + play, while the device sends 0x0E.

I think this stems from the fact that the very similar DDJ-400, from which the mapping was modified to create the flx4 mapping, does send 0x47. I think it fell through the cracks because the feature doesn't seem to be used all that often, I myself discovered the issue because I was trying to remap it to another behavior.

For reference, here's the DDJ-400 midi messages document and here the DDJ-FLX4 midi messages document. More conveniently here are the screenshots outlining the difference:

DDJ-FLX4

DDJ-400

Since last time, you guys asked me to base the PR off of branch 2.4, I'm doing the same thing here, let me know if I should rebase it off of another one or if anything else should be done.

[Swiftb0y]

Thank you very much for catching this. You're totally right with your conclusion that this was copied from the DDJ-400 and slipped through the cracks. LGTM.

[Swiftb0y]

fyi, in the future I recommend you create a separate feature branch. Without you're bound to run into trouble if you want to sync your own 2.4 branch with our upstream one.

[Aquassaut]

Thanks I'll make sure I do for anything more consequent. In this case I was not really that worried about the hard reset/force push on my end, but you're right.