As specified in the doc of spdk_for_each_channel:
```
Once 'fn' has been called on each channel, 'cpl' will be called
on the thread that spdk_for_each_channel was initially called from.
```
Fixes: ff87d29cc3 ("io_channel: Add mechanism to call a function on
each channel")
Change-Id: Ic60b061ec402672f510d99697943e96ff9a73417
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/369719
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>