MFC r310017, r310229, r312289, r327260, r329539, r329544-r329546, r329620,

r329729, r329911, r329999

r310017:
[spi] reformat message

This commit corrects print of nomatch (newline was too early)

Submitted by: Hiroki Mori <yamori813@yahoo.co.jp>
Reviewed by: ray, loos, mizhka
Differential Revision: https://reviews.freebsd.org/D8749

r310229:
ofw_spi: Parse property for the SPI mode and CS polarity.
As cs is stored in a uint32_t, use the last bit to store the
active high flag as it's unlikely that we will have that much CS.

Reviewed by: loos
Differential Revision: https://reviews.freebsd.org/D8614

r312289:
[spibus] small code refactoring

Merge 3 sequential printf calls into one.

Reported by: rpokala
Reviewed by: rpokala, adrian
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D8795

r327260:
SPDX: fix wrong license ID tag in dev/spibus.

r329539:
Provide public declarations for ofw_spibus_driver and ofw_spibus_devclass
so other drivers can refer to them in DRIVER_MODULE() decls.

r329544:
Add modules/spi as a gathering point for SPI-related modules, analagous to
modules/i2c for i2c/iicbus modules. Build spibus as a module.

r329545:
Add ofw_bus_if.h to SRCS.

r329546:
Build at45d and mx25l SPI flash drivers as modules.

r329620:
Add missing MODULE_DEPENDS().

r329729:
Remove some files that snuck in via cut and paste.

Having these compiled into the module causes the kobj method descriptors
to be resolved incorrectly (by the compile-time linker instead of the
kernel linker), which then leads to hours of frustrating debugging.

r329911:
Add a functional detach() routine, to make things kldunload-friendly.

r329999:
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".