Sorry, it’s not defined as “prvPAL_SetPlatformImageState” but the prvPAL_DefaultSetPlatformImageState function it is defined as does call prvPAL_SetPlatformImageState.
static OTA_Err_t prvPAL_DefaultSetPlatformImageState( uint32_t ulServerFileID,
OTA_ImageState_t eState )
{
( void ) ulServerFileID;
( void ) eState;
return prvPAL_SetPlatformImageState( eState );
}