regmap: Merge up fixes from mainline

There's several things here that will really help my CI.

diff --cc drivers/base/regmap/regcache-rbtree.c
Simple merge

diff --cc drivers/base/regmap/regcache.c
Simple merge

diff --cc drivers/base/regmap/regmap-kunit.c
Simple merge

diff --cc drivers/base/regmap/regmap.c
Simple merge