Adjust irdma_prep_for_unregister() definition to avoid clang 15 warning

Adjust irdma_prep_for_unregister() definition to avoid clang 15 warning

With clang 15, the following -Werror warning is produced:

    sys/dev/irdma/icrdma.c:621:26: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
    irdma_prep_for_unregister()
                             ^
                              void

This is because irdma_prep_for_unregister() is declared with a (void)
argument list, but defined with an empty argument list. Make the
definition match the declaration.

MFC after:	3 days