Cleanup MV/MD macros a little.

When using variadic macros there's no need for IF_MD2/IF_MV2 to deal
with function parameters. IF_MD/IF_MV are enough.

Throw in IF_MD_DRV/ID_MV_VOL that return the parameter if MD/MV, or 0
if not.

Change-Id: I7605e6039f3be19cb47110c84dcb3c5516f2c3eb
44 files changed