i2c: wmt: fix a bug when thread blocked

During each byte access, the host performs clock stretching.

To reduce the host performs clock stretching, move most of
the per-msg processing to the interrupt context.

Suggested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Hans Hu <hanshu-oc@zhaoxin.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>