drives/input: support ST7123 touchscreen controller

[fdcavalcanti]

Summary

Add support for ST7123 touchscreen controller (I2C only).
It requires board level init to register a callback, as polling mode is not supported.

• Add an I2C lower-half driver for the ST7123 capacitive touchscreen (drivers/input/st7123.c)
• Interrupt-driven only: board GPIO ISR calls st7123_interrupt_callback(), HPWORK reads the full touch frame and reports contacts via touch_event()
• Exposes /dev/inputN through the standard touchscreen upper half (multi-touch, DOWN/MOVE/UP, pressure, basic gestures)
• Document board integration under Documentation/components/drivers/character/input/st7123.rst

Datasheet: link

AI Disclaimer

AI agents used for code documentation only.

Impact

• New optional Kconfig: CONFIG_INPUT_ST7123 (default off); no effect unless selected
• Boards must wire I2C + INT and call st7123_register() / st7123_interrupt_callback(); polling is not supported
• Apps read struct touch_sample_s; multi-touch needs a buffer sized with SIZEOF_TOUCH_SAMPLE_S(n)

Testing

Tested on esp32p4-tab5.
Device is working as expected. Here's the output from tc_main (touchscreen example):

nsh> tc
tc_main: nsamples: 0
tc_main: Opening /dev/input0
`

Touching corner:

Sample     :
   npoints : 1
Point 1    :
        id : 0
     flags : 39
         x : 66
         y : 58
         h : 0
         w : 0
  pressure : 46
  gesture  : ff
 timestamp : 5680000

Touch middle:

Sample     :
   npoints : 1
Point 1    :
        id : 0
     flags : 1c
         x : 380
         y : 597
         h : 0
         w : 0
  pressure : 15
  gesture  : 00
 timestamp : 88860000

[acassis]

Hi @fdcavalcanti please fix this CI issue:

❌ Missing git commit message
Used config files:
    1: .codespellrc
Some checks failed. For contributing guidelines, see:
  https://github.com/apache/nuttx/blob/master/CONTRIBUTING.md

[github-actions]

MemBrowse Memory Report

No memory changes detected for:

• arduino-mega2560
• esp32-devkitc
• hifive1-revb
• mirtoo
• qemu-armv8a
• qemu-intel64
• rx65n-rsk2mb
• s698pm-dkit
• stm32-nucleo-f103rb

[fdcavalcanti]

@xiaoxiang781216 all fixes applied, thanks for the review!

[xiaoxiang781216]

how to support the multiple instances? let's remove this global variable