[FIX] prevent issue
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| CID | Type | File | Function |
|--------------------------------------------------------------------------------------|
| 453611 | Dereference null return value | daemon/sys_stat.c | get_device_network_type |
|--------------------------------------------------------------------------------------|
Change-Id: Icca85037dedbc86692579c1ab00130f6cb52bb39
Signed-off-by: Vitaliy Cherepanov <v.cherepanov@samsung.com>