i2c: spacemit: introduce pio for k1

i2c: spacemit: introduce pio for k1

This patch introduces I2C PIO functionality for the Spacemit K1 SoC,
enabling the use of I2C in atomic context.

When i2c xfer_atomic is invoked, use_pio is set accordingly.

Since an atomic context is required, all interrupts are disabled when
operating in PIO mode. Even with interrupts disabled, the bits in the
ISR (Interrupt Status Register) will still be set, so error handling can
be performed by polling the relevant status bits in the ISR.

Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260207-b4-k3-i2c-pio-v7-2-626942d94d91@linux.spacemit.com