2976 remove useless offsetof() macros

*** 30,39 ****
--- 30,40 ----
  #ifdef  __cplusplus
  extern "C" {
  #endif
  
  #include <sys/list.h>
+ #include <sys/sysmacros.h>
  #include <sys/usb/usba/usbai_private.h>
  #include <sys/videodev2.h>
  #include <sys/usb/clients/video/usbvc/usbvc.h>
  
  typedef struct usbvc_state usbvc_state_t;
*** 171,182 ****
  #define PRINT_MASK_HOTPLUG      0x00000080
  #define PRINT_MASK_DEVCTRL      0x00000100
  #define PRINT_MASK_DEVMAP       0x00000200
  #define PRINT_MASK_ALL          0xFFFFFFFF
  
- #define offsetof(s, m)  ((size_t)(&(((s *)0)->m)))
- 
  #define USBVC_MAX_PKTS 40
  
  #define USBVC_DEFAULT_READ_BUF_NUM 3
  #define USBVC_MAX_READ_BUF_NUM 40
  #define USBVC_MAX_MAP_BUF_NUM 40
--- 172,181 ----