SMUFF => SMuFF (#21243)

Marlin/Configuration.h

  *   PRUSA_MMU1      : Průša MMU1 (The "multiplexer" version)
  *   PRUSA_MMU2      : Průša MMU2
  *   PRUSA_MMU2S     : Průša MMU2S (Requires MK3S extruder with motion sensor, EXTRUDERS = 5)
- *   SMUFF_EMU_MMU2  : Technik Gegg SMUFF (Průša MMU2 emulation mode)
- *   SMUFF_EMU_MMU2S : Technik Gegg SMUFF (Průša MMU2S emulation mode)
+ *   SMUFF_EMU_MMU2  : Technik Gegg SMuFF (Průša MMU2 emulation mode)
+ *   SMUFF_EMU_MMU2S : Technik Gegg SMuFF (Průša MMU2S emulation mode)
  *
  * Requires NOZZLE_PARK_FEATURE to park print head in case MMU unit fails.
  * See additional options in Configuration_adv.h.

Marlin/src/inc/Conditionals_LCD.h

   #undef DISABLE_INACTIVE_EXTRUDER
 #endif
 
-// Průša MMU1, MMU 2.0, MMUS 2.0 and SMUFF force SINGLENOZZLE
+// Průša MMU1, MMU 2.0, MMUS 2.0 and SMuFF force SINGLENOZZLE
 #if HAS_MMU
   #define SINGLENOZZLE
 #endif

Marlin/src/inc/SanityCheck.h

 #endif
 
 /**
- * Multi-Material-Unit 2 / SMUFF requirements
+ * Multi-Material-Unit 2 / SMuFF requirements
  */
 #if HAS_PRUSA_MMU2
   #if EXTRUDERS != 5