fixed-point-tests: Run the tests for each possible parameter size

A lot of parameters were duplicated because we had one parameter for each size
(8, 16 and 32) and for each integral/fractional combination. However, they were
all at the root of the subsystem and a lot overlapped, e.g., q1.2 for 32bits
and q1.2 for 16 bits.

We fix this by:
 - Adding a ParameterBlock for each size
 - Modifying the tests to account for the change in the parameter paths
 - Run the tests for 8, 16 and 32 bits

Signed-off-by: David Wagner <david.wagner@intel.com>