[flang] Fix use-associated false-positive error

For the program provided as the test case flang fired the following
error:

    error: Semantic errors in main.f90
    error: 'foo' is not a procedure

This change fixes the error by postponing handling of `UseErrorDetails`
from `CharacterizeProcedure` to a later stage.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D125791