i2c: rcar: Revert the latest refactoring series

This whole series caused sometimes timeouts and even OOPSes on some
r8a7791 Koelsch boards. We need to understand and fix those first.

Revert "i2c: rcar: clean up after refactoring"
Revert "i2c: rcar: revoke START request early"
Revert "i2c: rcar: check master irqs before slave irqs"
Revert "i2c: rcar: don't issue stop when HW does it automatically"
Revert "i2c: rcar: init new messages in irq"
Revert "i2c: rcar: refactor setup of a msg"
Revert "i2c: rcar: remove spinlock"
Revert "i2c: rcar: remove unused IOERROR state"
Revert "i2c: rcar: rework hw init"

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>