wdparams from short into u_short. If wdp_cylinders is short, it
overflows and cause serious sign extension bug when large IDE HDD is
used. These members are only used for initialization of u_long
variables in both 3.0-current and RELENG_2_2 branch.
I believe this should be in 2.2.
Reviewed by: Bruce Evans <bde@zeta.org.au>