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

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

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

arm/arm64 freescale: Remove unused devclass arguments to DRIVER_MODULE.

Remove unused spibus_devclass and ofw_spibus_devclass.

Create new wrapper function: bus_delayed_attach_children()

Delay the attachment of children, when requested, until after interrutps are
running. This is often needed to allow children to run transactions on i2c or
spi busses. It's a common enough idiom that it will be useful to have its own
wrapper.

Reviewed by: ian
Differential Revision: https://reviews.freebsd.org/D21465

Mark the imx_spi device busy while transfers are in progress, so that the
module can't be unloaded while interrupts are pending.

Add pnp info to the imx_spi driver.

Defer attaching the spibus until timers and interrupts are working. The
driver requires interrupts to do transfers, and the drivers for the SPI
devices on the bus quite reasonably expect to be able to do IO while probing
and attaching.

Do not stop the loop that configures gpio chipselect pins on the first
error, just ignore pins that don't configure and keep setting up the ones
that do. (But when bootverbose is on, whine about the errors.)

Add a SPI driver for imx5 and imx6.

It can be compiled into the kernel with "device imx_spi" or loaded as a
module, which is also named "imx_spi".