Move some SD comments

Marlin/src/HAL/HAL_SAMD51/HAL.cpp

     dma_init();
   #endif
   #if ENABLED(SDSUPPORT)
-    #if SD_CONNECTION_IS(ONBOARD) && PIN_EXISTS(SD_DETECT)    // SD_DETECT_PIN may be remove when NO_SD_HOST_DRIVE is not defined in configuration_adv
+    // SD_DETECT_PIN may be removed if NO_SD_HOST_DRIVE is not defined in Configuration_adv.h
+    #if SD_CONNECTION_IS(ONBOARD) && PIN_EXISTS(SD_DETECT)
       SET_INPUT_PULLUP(SD_DETECT_PIN);
     #endif
     OUT_WRITE(SDSS, HIGH);  // Try to set SDSS inactive before any other SPI users start up

Marlin/src/inc/Conditionals_post.h

   #endif
 #endif
 
-//
-// The external SD card is not used. Hardware SPI is used to access the card.
-// When sharing the SD card with a PC we want the menu options to
-// mount/unmount the card and refresh it. So we disable card detect.
-//
 #if ENABLED(SDSUPPORT)
   #if SD_CONNECTION_IS(ONBOARD) && DISABLED(NO_SD_HOST_DRIVE)
+    //
+    // The external SD card is not used. Hardware SPI is used to access the card.
+    // When sharing the SD card with a PC we want the menu options to
+    // mount/unmount the card and refresh it. So we disable card detect.
+    //
     #undef SD_DETECT_PIN
     #define SHARED_SD_CARD
   #endif