Merge common XPT_CALC_GEOMETRY functions into a single convenience function.
Devices below may experience a change in geometry.

• Due to a bug, aic(4) never used extended geometry. Changes all drives >1G to now use extended translation.
• sbp(4) drives exactly 1 GB in size now no longer use extended geometry.
• umass(4) drives exactly 1 GB in size now no longer use extended geometry.

For all other controllers in this commit, this should be a no-op.

PR:
Submitted by:
Looked over by: scottl
Approved by:
Obtained from:
MFC after: