19880: drivers/ft5x06: fix initialization if callback function parameter is NULL r=aabadie a=gschorcht
### Contribution description
This PR fixes the `ft5x06` driver initialization if the callback function parameter `cb` is `NULL. This might be the case for example if the application uses the touch device in polling mode.
If the interrupt pin is initialized if the callback function parameter `cb` is `NULL`, the driver crashes the first time an interrupt is triggered. Therefore, the INT pin must be initialized only if also the callback function parameter `cb` is not `NULL`.
To be able to test the polling mode, this PR also includes a change of the `tests/drivers/ft5x06` application which introduces the environment variables `FT5X06_POLLING_MODE` `FT5X06_POLLING_PERIOD` and in the makefile.
### Testing procedure
1. Use any board with a FTXXXX touch device and test it in polling mode, for example:
```
FT5X06_POLLING_MODE=1 BOARD=stm32f746g-disco make -C tests/drivers/ft5x06 flash term
```
It should work as expected.
```
main(): This is RIOT! (Version: 2023.10-devel-119-g92a44a-drivers/ft5x06_fix_cb_null)
FT5x06 test application
+------------Initializing------------+
Initialization successful
1 touch detected
Touch 1 - X: 236, Y:111
Touch 1 - X: 236, Y:111
...
Touch 1 - X: 236, Y:111
Released!
```
2. Checkout master branch and cerry-pick commit 691a5e6308426ddc685e5a2c297238529211c258. The test application `tests/drivers/ft5x06` will crash once a touch event occur:
```
+------------Initializing------------+
Initialization successful
1 touch detected
Context before hardfault:
```
### Issues/PRs references
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
The interrupt mode has to be configured independent on whether the INT pin is initialized already by the `ft5x06_init` function if parameter `cb` is defined or later, for example by the `touch_dev` implementation.
To obtain coordinates from the touch panel that correspond to the display coordinates, it is often necessary to convert the coordinates from the touch display by swapping and mirroring. For the sake of simplicity, possible rotations are additionally defined.
If the INT pin is initialized if the callback function parameter `cb` is `NULL`, the driver crashes the first time an interrupt is triggered. Therefore, the INT pin must be initialized only if also the callback function parameter `cb` is not `NULL`.
There is no need to copy the configuration parameter set to the device descriptor. A const pointer to the configuration parameter set in ROM is sufficient. It saves some 16 byte of RAM.
