i2c: ismt: dump registers at the end of transactions

This patch dumps general and master registers at the end of transactions
when debugging is enabled. Previously, registers were only dumped before
submitting new descriptors (at the beginning of transactions).

This helps debugging if some registers change as result of a failed
transaction (e.g. bits are set in the ERRSTS general register).

Signed-off-by: Radu Rendec <radu.rendec@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>