nvme: Fix memory leak on error path of nvme_init

nvme: Fix memory leak on error path of nvme_init

The use of log_msg_ret to log a message and return an error meant that
memory allocated earlier in the function was not freed on this error
path. Instead log the message in the same way that log_msg_ret would do
and then goto the cleanup code to free the memory.

This issue found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>