kernel/vm: Perform area ownership check before protection check.

This way we do not "leak" area protection status (not really a
significant concern at the moment, but might as well while I
was looking at this.)

src/system/kernel/vm/vm.cpp

@@ -2918,9 +2918,6 @@ vm_set_area_protection(team_id team, area_id areaID, uint32 newProtection,
 			return B_NOT_ALLOWED;
 		}
 
-		if (area->protection == newProtection)
-			return B_OK;
-
 		if (team != VMAddressSpace::KernelID()
 			&& area->address_space->ID() != team) {
 			// unless you're the kernel, you are only allowed to set
@@ -2928,6 +2925,9 @@ vm_set_area_protection(team_id team, area_id areaID, uint32 newProtection,
 			return B_NOT_ALLOWED;
 		}
 
+		if (area->protection == newProtection)
+			return B_OK;
+
 		isWritable
 			= (area->protection & (B_WRITE_AREA | B_KERNEL_WRITE_AREA)) != 0;