i2c: stm32f7: recover the bus on access timeout

When getting an access timeout, ensure that the bus is in a proper
state prior to returning the error.

Fixes: aeb068c5

 ("i2c: i2c-stm32f7: add driver")
Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>