platform/x86: hp-bioscfg: Change how enum possible values size is evaluated

Updates steps how enum possible values size is evaluated

Signed-off-by: Jorge Lopez <jorge.lopez2@hp.com>
Link: https://lore.kernel.org/r/20230731203141.30044-7-jorge.lopez2@hp.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>