qcacld-3.0: Remove macro CFG_ACTION_OUI_MAX_LEN

Previously change I6984096719a5abd7fa4f0a4f6641a17d29348332
("qcacld-3.0: Relocate HDD ini items (2)") added macro
CFG_ACTION_OUI_MAX_LEN, but did not add any code which uses it.
All of the Action OUI config items use ACTION_OUI_MAX_STR_LEN,
therefore remove the unused macro.

Change-Id: I8b194ebbbe901a4effef696014551346b3c52645
CRs-Fixed: 2365062

core/hdd/inc/hdd_config.h

@@ -745,8 +745,6 @@ enum hdd_wext_control {
  *
  */
 
-#define CFG_ACTION_OUI_MAX_LEN 256
-
 /*
  * <ini>
  * gEnableActionOUI - Enable/Disable action oui feature