regmap: Updates for v5.8

This has been a very active release for the regmap API for some reason,
a lot of it due to new devices with odd requirements that can sensibly
be handled here.

 - Add support for buses implementing a custom reg_update_bits()
   method in case the bus has a native operation for this.
 - Support 16 bit register addresses in SMBus.
 - Allow customization of the device attached to regmap-irq.
 - Helpers for bitfield operations and per-port field initializations.
Merge remote-tracking branch 'regmap/for-5.8' into regmap-next