chore(cpn): Allow configuring AUX serial port as "External module" (#2854)

* Add external module to hardware settings

* Use serial port aux1 rather than radio profile externalaccessmod
Move module conversion function from OpenTxFirmare to ModuleData

* Remove externalaccessmod from radio profile options

* Unnecessary CMake option HARDWARE_EXTERNAL_ACCESS_MOD removed.

---------

Co-authored-by: rotorman <risto.koiva@web.de>

radio/src/options.h

@@ -95,9 +95,6 @@ static const char * const options[] = {
 #if defined(SHUTDOWN_CONFIRMATION)
   "shutdownconfirm",
 #endif
-#if defined(HARDWARE_EXTERNAL_ACCESS_MOD)
-  "externalaccessmod",
-#endif
 #if defined(IMU_LSM6DS33)
   "lsm6ds33",
 #endif

radio/src/targets/horus/CMakeLists.txt

@@ -6,7 +6,6 @@ option(PXX2 "PXX2 protocol support" OFF)
 option(AFHDS3 "AFHDS3 TX Module" ON)
 option(MULTIMODULE "DIY Multiprotocol TX Module (https://github.com/pascallanger/DIY-Multiprotocol-TX-Module)" ON)
 option(GHOST "Ghost TX Module" ON)
-option(HARDWARE_EXTERNAL_ACCESS_MOD "Support for R9M 2019 hardware mod" OFF)
 option(SPACEMOUSE "Support for SpaceMouse" OFF)
 
 set(PWR_BUTTON "PRESS" CACHE STRING "Pwr button type (PRESS/SWITCH)")
@@ -189,12 +188,6 @@ if(NOT UNEXPECTED_SHUTDOWN)
   add_definitions(-DNO_UNEXPECTED_SHUTDOWN)
 endif()
 
-if(HARDWARE_EXTERNAL_ACCESS_MOD)
-  set(PXX2 ON)
-  set(AUX_SERIAL OFF)
-  add_definitions(-DHARDWARE_EXTERNAL_ACCESS_MOD)
-endif()
-
 if(IMU_LSM6DS33)
   add_definitions(-DIMU_LSM6DS33)
   set(AUX_SERIAL OFF)

radio/src/targets/horus/hal.h

@@ -849,7 +849,7 @@
 #define EXTMODULE_PWR_GPIO                 GPIOB
 #define EXTMODULE_PWR_GPIO_PIN             GPIO_Pin_3  // PB.03
 #define EXTERNAL_MODULE_PWR_OFF()          GPIO_ResetBits(EXTMODULE_PWR_GPIO, EXTMODULE_PWR_GPIO_PIN)
-#if (defined(PCBX10) && defined(PCBREV_EXPRESS)) || defined(HARDWARE_EXTERNAL_ACCESS_MOD)
+#if defined(PCBX10) && defined(PCBREV_EXPRESS)
   #define EXTMODULE_RCC_AHB1Periph         (RCC_AHB1Periph_GPIOB | RCC_AHB1Periph_DMA1)
   #define EXTMODULE_TX_GPIO                GPIOB
   #define EXTMODULE_USART_GPIO             EXTMODULE_TX_GPIO