EmbeddedPkg/NonCoherentIoMmuDxe: Make SetAttributes always succeed

NonCoherentIoMmuSetAttribute() does nothing except return
EFI_UNSUPPORTED. This was fine when it was introduced, but now, the PCI
bus driver will fail a PCI I/O Map() operation if the call to
SetAttributes() fails.

So return EFI_SUCCESS instead.

Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Abner Chang <abner.chang@amd.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>

EmbeddedPkg/Drivers/NonCoherentIoMmuDxe/NonCoherentIoMmuDxe.c

@@ -70,7 +70,7 @@ NonCoherentIoMmuSetAttribute (
   IN UINT64                IoMmuAccess
   )
 {
-  return EFI_UNSUPPORTED;
+  return EFI_SUCCESS;
 }
 
 /**