sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

altera drivers: Remove unused devclass arguments to DRIVER_MODULE.

altera: clean up empty lines in .c and .h files

Negate the logic of XCHAN_CAP_NOBUFS macro and rename it to
XCHAN_CAP_BOUNCE.

The only application that uses bounce buffering for now is the Government
Furnished Equipment (GFE) P2's dma core (AXIDMA) with its own dedicated
cacheless bounce buffer.

Sponsored by: DARPA, AFRL

o Rewrite softdma_process_tx() of Altera SoftDMA engine driver
so it does not require a bounce buffer. The only need for this was
to align the buffer address. Implement unaligned access and we don't
need to copy data twice.
o Remove contigmalloc-based bounce buffer from xDMA code since it is
not suitable for arbitrary memory provided by platform, which is
sometimes a dedicated piece of memory that is not managed by OS at all.

Sponsored by: DARPA, AFRL

Add driver for Altera SoftDMA® device.

SoftDMA is a software implementation of DMA engine built using Altera
FIFO component.

Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D9620