yaml_parser_mod: Use integral error code

[J-Lentz]

Description
PR #1563 introduced an error code which is returned by open_and_parse_file_wrap in yaml_parser_mod. This PR corrects the error code's type, which fixes a type mismatch error which occurs when building with the Cray compiler.

How Has This Been Tested?
Fixes the type mismatch error when building yaml_parser_mod with the Cray compiler.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• make distcheck passes

[uramirez8707]

Thank you for fixing this bug