MFC r236991:

Final whitespace trim.

Submitted by:	imp
Approved by:	marius
Obtained from:	Netflix
MFC r240177:

Dynamically allocate the S/G lists passed to callback routines rather than
allocating them on the stack of various bus_dmamap_load*() functions.  The
S/G lists are stored in the DMA tags.  This matches the implementation on
all other platforms.

Submitted by:	jhb
Approved by:	marius, adrian
Obtained from:	Netflix