app/test: update hash key size range and initial values

app/test: update hash key size range and initial values

Previous key sizes used for testing did not have much purpose.
This patch substitutes them with some more meaninful
(standard multiple of 2 key sizes, plus IPv4/v6 tuple and others)

Also an arbitrary initial value has been added to increase
the test coverage, and RTE_DIM macro is used to iterate the loops.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>