Contribution description

This PR improves the Kconfig submenu structure for ESP SoCs.

Without this PR, some ESP SoC specific configurations are shown in top menu and not in the ESP specific submenus:

• ESP8266

  (Top)
                                                               RIOT Configuration
      ESP8266 specific configurations  --->
      ESP configurations  --->
  [ ] Simulate ESP with QEMU
  [ ] Use software timer
  [ ] gdbstub interface support
  [*] RIOT Core  --->
  ...
  

• ESP32

  (Top)
                                                               RIOT Configuration
      ESP32 specific configurations  --->
  [ ] Use hardware counter
      ESP configurations  --->
  [ ] Simulate ESP with QEMU
  [*] RIOT Core  --->
  ...
  

With this PR, these ESP SoC specific configurations are moved to the appropriate submenus and give a much more structured view of the ESP specific configuration options:

• ESP8266

  (Top)
                                                               RIOT Configuration
      ESP8266 specific configurations  --->
      ESP configurations  --->
  [*] RIOT Core  --->
  ...
  

  (Top) → ESP8266 specific configurations
                                                               RIOT Configuration
      CPU clock frequency (80 MHz)  --->
  [ ] Use software timer as low-level timer peripheral
  [ ] gdbstub interface support
  

  (Top) → ESP configurations
                                                               RIOT Configuration
  [ ] Add additional information to the log output
  [ ] Add additional startup information to the log output
  [ ] Simulate ESP with QEMU
  

• ESP32

      ESP32 specific configurations  --->
      ESP configurations  --->
  [*] RIOT Core  --->
  ...
  

  (Top) → ESP32 specific configurations
                                                               RIOT Configuration
     CPU clock frequency (80 MHz)  --->
  [ ] SPI RAM support
  [*] Enable JTAG debugging interface
  [ ] Use hardware counter as low-level timer peripheral
  

  (Top) → ESP configurations
                                                               RIOT Configuration
  [ ] Add additional information to the log output
  [ ] Add additional startup information to the log output
  [ ] Simulate ESP with QEMU
  

Testing procedure

1. Green CI
2. Using

   TEST_KCONFIG=1 BOARD=esp8266-esp-12x make -C tests/periph_timer menuconfig
   TEST_KCONFIG=1 BOARD=esp32-wrover-kit make -C tests/periph_timer menuconfig
   

   should show the configuration menu structure.

Issues/PRs references