i2c: spacemit: fix detect issue

i2c: spacemit: fix detect issue

This commit addresses two issues causing i2c detect to fail.

The identified issues are:

1. Incorrect error handling for BED (Bus Error No ACK/NAK):
   Before this commit, Both ALD (Arbitration Loss Detected) and
   BED returned -EAGAIN.
2. Missing interrupt status clear after initialization in xfer():
   On the K1 SoC, simply fixing the first issue changed the error
   from -EAGAIN to -ETIMEOUT. Through tracing, it was determined that
   this is likely due to MSD (Master Stop Detected) latency issues.

   That means the MSD bit in the ISR may still be set on the next transfer.
   As a result, the controller won't work — we can see from the scope that
   it doesn't issue any signal.
   (This only occurs during rapid consecutive I2C transfers.
   That explains why the issue only shows up with i2cdetect.)

With these two fixes, i2c device detection now functions correctly on the K1 SoC.

Fixes: 5ea558473fa31 ("i2c: spacemit: add support for SpacemiT K1 SoC")
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Tested-by: Michael Opdenacker <michael.opdenacker@rootcommit.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20251113-fix-k1-detect-failure-v2-1-b02a9a74f65a@linux.spacemit.com