samd: Remove "makefile" file.

This file can be added by a user to customise the build process.

ports/samd/makefile

@@ -1,12 +0,0 @@
-#BOARD = TRINKET
-UF2DEV = /dev/sdb
-#UF2CONV = /home/damien/others/uf2/utils/uf2conv.py
-
-include Makefile
-
-deploy: $(BUILD)/firmware.uf2
-	$(ECHO) "Copying $< to the board"
-	mount $(UF2DEV)
-	cat /mnt/INFO_UF2.TXT > /dev/null
-	cp $< /mnt
-	umount /mnt