[Feature][T8TSK-251] add get security boot flag API in misc

Only Configure:No
Affected branch:GSW3.0-No-Connman
Affected module:misc
Is it affected on both ZXIC and MTK: only MTK
Self-test: Yes
Doc Update: Need

Change-Id: I873d746ab817a5f88fb27372aeb60b79cdfd2b66
6 files changed