lcd_hd44780: Implement support for HD44780 compatible LCDs.
lcd_hd44780: Get rid of some unnecessary delays in the 4-bit interface.

There is no need to wait for 50 us between nibble writes and reads.
lcd_hd44780: Convert #defines to static constexprs.
lcd_hd44780: Add an example program.
Merge remote-tracking branch 'upstream/pinset' into lcd_hd44780
lcd_hd44780: Fix a comment to refer to data delay in the low-voltage case.
pinset: Add const qualifier to fix compilation.

Also fixed the pinset test.
tests: Fix reg_start in port test.
lcd_hd44780: Convert to use a Pinset.
lcd_hd44780: Support 8-bit interfaces.
lcd_hd44780: Rename all init() methods to setup().