MediaPlayerService: avoid invalid static cast

Bug: 30204103
Change-Id: Ie0dd3568a375f1e9fed8615ad3d85184bcc99028
(cherry picked from commit ee0a0e39acdcf8f97e0d6945c31ff36a06a36e9d)

void MediaPlayerService::AudioOutput::setMinBufferCount()
{
 char value[PROPERTY_VALUE_MAX];
 if (property_get("ro.kernel.qemu", value, 0)) {
        mIsOnEmulator = true;
        mMinBufferCount = 12; // to prevent systematic buffer underrun for emulator
 }
}

void MediaPlayerService::AudioOutput::setMinBufferCount()
{
 char value[PROPERTY_VALUE_MAX];
 if (property_get("ro.kernel.qemu", value, 0)) {
        mIsOnEmulator = true;
        mMinBufferCount = 12; // to prevent systematic buffer underrun for emulator
 }
}
