tests: sparse-fiemap: adjust syntax to accommodate older awk

tests: sparse-fiemap: adjust syntax to accommodate older awk

* tests/cp/sparse-fiemap: Parenthesize ternary expression used
as an argument to awk's printf.  Otherwise, gawk 3.0.1 and the
one from debian stable's original-awk would get a syntax error.
Reported by Dennis Clarke.

Copyright note: tiny change