code_relocation: use booleans for string_create_helper arguments

The string_create_helper function has the arguments: load_address_in_flash
and is_copy. These arguments take logical values, but previously the
calling code used 1 and 0 rather than the more idiomatic True and False.

This patch corrects the issue by replacing use of int values with bool
values.

Signed-off-by: Joel Holdsworth <jholdsworth@nvidia.com>