2976 remove useless offsetof() macros

@@ -30,10 +30,11 @@
 #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;

@@ -171,12 +172,10 @@
 #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