userlandfs: Only add kernel flags in RequestAllocator in _KERNEL_MODE.

Otherwise, create_area fails with "Invalid Argument." Should fix the
"empty directory in userlandfs mount" bug that has been appearing
since the cloneable-area fixes.

Change-Id: I26e73539a9f345e76b22a34a68fe4b49c63683c2
Reviewed-on: https://review.haiku-os.org/707
Reviewed-by: waddlesplash <[email protected]>

src/add-ons/kernel/file_systems/userlandfs/private/RequestAllocator.cpp

@@ -240,7 +240,11 @@ RequestAllocator::AllocateAddress(Address& address, int32 size, int32 align,
 			B_ANY_ADDRESS,
 #endif
 			areaSize, B_NO_LOCK,
-			B_READ_AREA | B_WRITE_AREA | B_USER_CLONEABLE_AREA);
+			B_READ_AREA | B_WRITE_AREA
+#ifdef _KERNEL_MODE
+				| B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA | B_USER_CLONEABLE_AREA
+#endif
+			);
 		if (area < 0)
 			RETURN_ERROR(area);
 		fAllocatedAreas[fAllocatedAreaCount++] = area;