19355: boards/adafruit-itsybitsy-m4: configure littleFS on external flash r=aabadie a=benpicco
19883: drivers/stmpe811: introduce conversion for X and Y coordinates r=aabadie a=gschorcht
### Contribution description
To obtain coordinates from the touch panel that correspond to the display coordinates, it is often necessary to convert the coordinates by swapping and mirroring. Instead of hard coding this conversion, it is now controlled by an additional conversion parameter. For the sake of simplicity, possible rotations are predefined.
The PR fixes `tests/pkg/lgvl_touch` for the `stm32f429i-disc1` board where the coordinates from the touch panel seem to be mirrored in relation to the screen coordinates at the vertical axis.
### Testing procedure
Flash `tests/pkg/lvgl_touch`. Without this PR the coordinates of the button don't correspond to the touch panel coordinates once the button has been pressed. Instead they seem to be mirrored at the vertical axis. With this PR, the coordinates should be correct.
### Issues/PRs references
Co-authored-by: Benjamin Valentin <benpicco@beuth-hochschule.de>
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
