osi: Return 0 on osi_property_get failure

// PROPERTY_VALUE_MAX - 1 and will always be zero terminated.

// (the length does not include the terminating zero).

// If the property read fails or returns an empty value, the |default_value|

// is used (if nonnull).

// is used (if nonnull).  If the |default_value| is null, zero is returned.

int osi_property_get(const char* key, char* value, const char* default_value);

// Write value of property associated with key |key| to |value|.

int osi_property_get(const char* key, char* value, const char* default_value) {

#if defined(OS_GENERIC)

  /* For linux right now just return default value, if present */

  int len = -1;

  int len = 0;

  if (!default_value) return len;

  len = strlen(default_value);