Fixed typo in var name BOARDS_TXT in Sam.mk
Fixed typo in var name BOARDS_TXT in Sam.mk

marioaugustorama/Arduino-Makefile,sudar/Arduino-Makefile,WeAreLeka/Arduino-Makefile,sudar/Arduino-Makefile,marioaugustorama/Arduino-Makefile,WeAreLeka/Arduino-Makefile,sej7278/Arduino-Makefile,tuna-f1sh/Arduino-Makefile,sej7278/Arduino-Makefile,tuna-f1sh/Arduino-Makefile,WeAreLeka/Arduino-Makefile