Fix BL Touch debug leveling

[FabioBatSilva]

Hi..

First time contributing here and its been a long time since I wrote any cpp..
Please let me know if I messed something here..

Description

Looks like #14839 introduced a issue when DEBUG_LEVELING_FEATURE is defined
Where SERIAL_ECHO* is called with the wrong number of arguments..

if I define

#define BLTOUCH
#define DEBUG_LEVELING_FEATURE

There is a compilation error when running pio run

RCH_AVR -DARDUINO=10805 -IMarlin -I/Users/fabio/.platformio/packages/framework-arduinoavr/libraries/__cores__/arMarlin/Marlin_main.cpp:2128:78: error: macro "SERIAL_ECHOLNPAIR" requires 2 arguments, but only 1 given
         if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPAIR("BLTouch DEPLOY requested");
                                                                              ^
Marlin/Marlin_main.cpp:2135:105: error: macro "SERIAL_ECHOLNPAIR" requires 2 arguments, but only 1 given
           if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPAIR("BLTouch ALARM or TRIGGER after DEPLOY, recovering");
                                                                                                         ^
Marlin/Marlin_main.cpp:2144:81: error: macro "SERIAL_ECHOLNPAIR" requires 2 arguments, but only 1 given
             if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPAIR("BLTouch Recovery Failed");
                                                                                 ^
Marlin/Marlin_main.cpp:2163:79: error: macro "SERIAL_ECHOLNPAIR" requires 2 arguments, but only 1 given
         if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPAIR("bltouch.deploy_proc() end");
                                                                               ^
Marlin/Marlin_main.cpp:2172:76: error: macro "SERIAL_ECHOLNPAIR" requires 2 arguments, but only 1 given
         if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPAIR("BLTouch STOW requested");

Benefits

Use SERIAL_ECHO instead of SERIAL_ECHOLNPAIR to write a single
Use SERIAL_ECHOLNPGM instead of undefined DEBUG_ECHOLNPAIR ?

Related Issues

#14839

[tpruvot]

SERIAL_ECHO doesnt put "\n", need SERIAL_ECHOLN

Marlin/src/core/serial.h:70:#define SERIAL_ECHO(x)          SERIAL_OUT(print, x)
Marlin/src/core/serial.h:72:#define SERIAL_ECHOLN(x)        SERIAL_OUT(println, x)

[thinkyhead]

SERIAL_ECHOLNPGM is even better!