get.sh: make xbmkget() easier to understand

the intent once again is that this for loop shall
return, with zero status, if success is observed.

otherwise, the loop breaks and an error is thrown.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/get.sh

@@ -85,8 +85,10 @@ xbmkget()
 	echk="f" && [ "$1" = "git" ] && echk="d"
 
 	for url in "$2" "$3"; do
-		[ -n "$url" ] && try_file "$url" "$@" && \
-		    eval "[ -$echk \"$4\" ] && return 0"
+		[ -n "$url" ] || continue
+		try_file "$url" "$@" || continue
+		eval "[ -$echk \"$4\" ] || continue"
+		return 0 # successful download/copy
 	done
 	err "$1 $2 $3 $4: not downloaded"; :
 }