SoundTriggerHalLegacy.cpp: include errno.h

frameworks/av/services/soundtrigger/SoundTriggerHalLegacy.cpp:72:17: error: use of undeclared identifier 'ENODEV'
        return -ENODEV;
                ^
frameworks/av/services/soundtrigger/SoundTriggerHalLegacy.cpp:83:17: error: use of undeclared identifier 'ENODEV'
        return -ENODEV;
                ^
frameworks/av/services/soundtrigger/SoundTriggerHalLegacy.cpp:91:17: error: use of undeclared identifier 'ENODEV'
        return -ENODEV;
                ^
frameworks/av/services/soundtrigger/SoundTriggerHalLegacy.cpp:102:17: error: use of undeclared identifier 'ENODEV'
        return -ENODEV;
                ^
frameworks/av/services/soundtrigger/SoundTriggerHalLegacy.cpp:110:17: error: use of undeclared identifier 'ENODEV'
        return -ENODEV;
                ^
frameworks/av/services/soundtrigger/SoundTriggerHalLegacy.cpp:118:17: error: use of undeclared identifier 'ENODEV'
        return -ENODEV;
                ^
frameworks/av/services/soundtrigger/SoundTriggerHalLegacy.cpp:124:13: error: use of undeclared identifier 'ENOSYS'
    return -ENOSYS;
            ^

Change-Id: I3bd324de2e73a757d654d0f255873cfc7cc064e7