regmap-irq: Remove virtual registers

No remaining users, and it's been replaced by config registers.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Link: https://lore.kernel.org/r/20230509110100.3980123-3-aidanmacdonald.0x0@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>