platformio.ini: do not redefine "register" as it break ASM code and affects methods called "register" as well

unfortunately this breaks build for -C3 and -S3

/.platformio/packages/framework-arduinoespressif32/tools/sdk/esp32c3/include/riscv/include/riscv/semihosting.h:75:19: warning: ignoring asm-specifier for non-static local variable 'a0'
     register long a0 asm ("a0") = id;
                   ^~
.platformio/packages/framework-arduinoespressif32/tools/sdk/esp32c3/include/riscv/include/riscv/semihosting.h:76:19: warning: ignoring asm-specifier for non-static local variable 'a1'
     register long a1 asm ("a1") = (long) data;

Author: softhack007

platformio.ini

@@ -111,7 +111,7 @@ build_flags =
   -D DECODE_SONY=true
   -D DECODE_SAMSUNG=true
   -D DECODE_LG=true
-  -Dregister= # remove warnings in C++17 due to use of deprecated register keyword by the FastLED library
+  ; -Dregister= # remove warnings in C++17 due to use of deprecated register keyword by the FastLED library
   -DWLED_USE_MY_CONFIG
   ; -D USERMOD_SENSORSTOMQTT
   #For ADS1115 sensor uncomment following