ada: Remove redundant suppression for non-modified IN OUT parameters

ada: Remove redundant suppression for non-modified IN OUT parameters

Non-modified IN OUT parameters are first collected and then filtered by
examining uses of their enclosing subprograms. In this filtering we
don't need to look again at properties of the formal parameters
themselves.

Cleanup related to improved detection of references to uninitialized
objects; semantics is unaffected.

gcc/ada/

	* sem_warn.adb
	(No_Warn_On_In_Out): For subprograms we can simply call
	Warnings_Off.
	(Output_Non_Modified_In_Out_Warnings): Remove repeated
	suppression.