sys: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

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

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

usb: Remove unused devclass arguments to DRIVER_MODULE.

usb: Use __diagused for variables only used in KASSERT().

cp2112iic_intr_write_callback: eliminate write only variable psc

Sponsored by: Netflix

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

cp2112: a number of cleanups and improvements

- hoist all request / response structures from function level to top level
- replace magic numeric literals with constants
- regroup types, data and functions
- remove setting of the id field in responses as they are completely
overwritten with data from the device
- centralize setting of the id field as it is always set to the value of
request type
- fix setting and querying of open-drain vs push-pull configuration of
an output pin -- it's always in one of those configurations
- detect special pin configurations: a pin in a special configuration is
neither general purpose input or output
- there is still no support for setting special configurations

MFC after: 2 weeks

cp2112: driver for the namesake GPIO and I2C master gadget

Documentation:
- CP2112 Datasheet
https://www.silabs.com/documents/public/data-sheets/cp2112-datasheet.pdf
- AN495: CP2112 Interface Specification
https://www.silabs.com/documents/public/application-notes/an495-cp2112-interface-specification.pdf
- CP2112 Errata
https://www.silabs.com/documents/public/errata/cp2112-errata.pdf

The logic is implemented as three sub-drivers.
The parent driver claims the USB device and creates two child devices.
One acts as a GPIO controller and the other is an I2C controller.

Tested with CP2112 revision F02.
Both features seem to work.
HTU21 sensor was used as an I2C slave.

Reviewed by: adrian, hselasky
MFC after: 2 weeks
Relnotes: maybe
Differential Revision: https://reviews.freebsd.org/D25359