[flang] Fix for array upper bounds with *

Even though the array is declared with '*' upper bounds, it has an
initial value that has a statically known shape. Use the shape from
the type of the initializer when the declared size is '*'.

This patch is part of the upstreaming effort from fir-dev branch.

Reviewed By: jeanPerier

Differential Revision: https://reviews.llvm.org/D128889



Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>