Fix svace issues

Fix svace issues

- 410071: fixed memory leak problem due to dynamic allocated 'devices'
- 410077: fixed memory leak that is not freed because the dynamic
allocated 'cmd' variable is called through multiple callback function.
- 410083: fixed memory leak that do not free 'uuid_str' variable which
allocated by g_strdup().
- 410084: fixed a problem that does not free the variables allocated to
heap during mdgd_iot_initialize() when calling mdgd_iot_deinitialize()

Change-Id: I88e824bac894ae2f51c8310109d1242c36737c70
Signed-off-by: Jihoon Jung <jh8801.jung@samsung.com>