Fix/smooth quant param grid

[Aryanpagaria]

Changes

Fixed a subtle bug in _get_smooth_quant_param_grid where matmul values were returned as single-element tuples instead of plain floats.

Replaced:
AdvancedSmoothQuantParameters(matmul=alpha_v) for alpha_v in itertools.product(alpha_values)
With:
AdvancedSmoothQuantParameters(matmul=alpha_v) for alpha_v, in itertools.product(alpha_values)
This ensures matmul values are floats, preventing TypeError in the PTQ pipeline.

Reason for changes

itertools.product always returns tuples, even for a single iterable.
Previously, this caused a crash when the code tried to compare sq_params.matmul >= 0 because tuples cannot be compared to integers.
The change fixes this by unpacking the single-element tuples to get plain float values.

Related tickets

Closes #3613

Tests

Verified manually that _get_smooth_quant_param_grid() now returns AdvancedSmoothQuantParameters with float matmul values, e.g., 0.15, 0.25, instead of (0.15,).
Results of test :
0.15 <class 'float'>
0.25 <class 'float'>
0.5 <class 'float'>
...

Ran existing pytest suite — all tests passed successfully.

No new tests were required as the logic is unchanged, only the tuple unpacking was fixed.

[ljaljushkin]

@andrey-churkin, could you please take a look?