qcacld-3.0: Define A_OFFSETOF macro

Define A_OFFSETOF macro to fix compilation
errors.

A_OFFSETOF macro is mapped to macro offsetof()
defined in stddef.h.

Change-Id: I766826d610fcb6a06775f07bcd8a041ee29be89b
CRs-Fixed: 2967130

uapi/linux/osapi_linux.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2018 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2013-2018, 2021 The Linux Foundation. All rights reserved.
  *
  * Permission to use, copy, modify, and/or distribute this software for
  * any purpose with or without fee is hereby granted, provided that the
@@ -73,6 +73,7 @@
 #define A_PRINTF(args ...) \
 	QDF_TRACE_ERROR(QDF_MODULE_ID_QDF, args)
 #define A_SNPRINTF(buf, len, args ...)   snprintf(buf, len, args)
+#define A_OFFSETOF(type, field)   offsetof(type, field)
 
 /*
  * Timer Functions