toradex: tdx-cfg-block: Cleanup interactive cfg block creation

Simplify interactive config block creation code, instead of having a
a long list of questions and a complex tree of preprocessor directive to
guess the exact SKU, just ask the user to select it from a list.

The modules list is filtered out to include only SKUs that are supported
by the specific u-boot binary in execution.

Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>