Removed 2 arguments from l4_capability_control

l4_capability_control works well for almost all system calls
using a buffer pointer to the capability that it operates on.

Only for sharing/granting of capability lists, it is yet to be
decided how to provide a grant target id.

src/api/cap.c

@@ -626,10 +626,9 @@ int cap_replicate(struct capability *dupl)
 }
 
 /*
- * Read, manipulate capabilities. Currently only capability read support.
+ * Read, manipulate capabilities.
  */
-int sys_capability_control(unsigned int req, unsigned int flags,
-			   l4id_t capid, l4id_t target, void *userbuf)
+int sys_capability_control(unsigned int req, unsigned int flags, void *userbuf)
 {
 	int err = 0;