EAP-pwd: Remove unused checks for cofactor > 1 cases

EAP-pwd: Remove unused checks for cofactor > 1 cases

None of the ECC groups supported in the implementation had a cofactor
greater than 1, so these checks are unreachable and for all cases, the
cofactor is known to be 1. Furthermore, RFC 5931 explicitly disallow use
of ECC groups with cofactor larger than 1, so this checks cannot be
needed for any curve that is compliant with the RFC.

Remove the unneeded group cofactor checks to simplify the
implementation.

Signed-off-by: Jouni Malinen <j@w1.fi>