i2c: rcar: faster irq code to minimize HW race condition

i2c: rcar: faster irq code to minimize HW race condition

[ Upstream commit c7b514ec979e23a08c411f3d8ed39c7922751422 ]

To avoid the HW race condition on R-Car Gen2 and earlier, we need to
write to ICMCR as soon as possible in the interrupt handler. We can
improve this by writing a static value instead of masking out bits.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>