Remove references to obsoleted REAL_CALL from documentation.

src/arch/i386/include/realmode.h

  */
 
 /*
- * REAL_CALL ( routine, num_out_constraints, out_constraints,
- *	       in_constraints, clobber )
  * REAL_EXEC ( name, asm_code_str, num_out_constraints, out_constraints,
  *	       in_constraints, clobber )
  *
- * If you have a pre-existing real-mode routine that you want to make
- * a far call to, use REAL_CALL.  If you have a code fragment that you
- * want to copy down to base memory, execute, and then remove, use
- * REAL_EXEC.
- *
  * out_constraints must be of the form OUT_CONSTRAINTS(constraints),
  * and in_constraints must be of the form IN_CONSTRAINTS(constraints),
  * where "constraints" is a constraints list as would be used in an

src/arch/i386/transitions/librm.S

  * callee to preserve.  Gate A20 will be re-enabled in case the
  * real-mode routine disabled it.
  *
- * librm.h defines two convenient macros for using real_call:
- * REAL_CALL and REAL_EXEC.  See librm.h and realmode.h for details
- * and examples.
+ * librm.h defines a convenient macro REAL_EXEC() for using real_call.
+ * See librm.h and realmode.h for details and examples.
  *
  * Parameters:
  *   (32-bit) near pointer to real-mode function to call