Linux has two defines to check dmi data. DMI_MATCH checks if the dmi
string includes substr. DMI_EXACT_MATCH checks if the dmi string exactly
matches substr. Compat layer should have the same behaviour.
The new definition of dmi_strmatch shouldn't break any driver. A driver
would break if it uses the highest bit of the slot field. Nevertheless,
linux uses the same definition and FreeBSD uses dmi_field values as slot
which are lower than 128.