cxl: Compile with -Werror

It's a good idea, and it brings us in line with the rest of arch/powerpc.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Acked-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/drivers/misc/cxl/Makefile b/drivers/misc/cxl/Makefile
index 14e3f82..6f484df 100644
--- a/drivers/misc/cxl/Makefile
+++ b/drivers/misc/cxl/Makefile
@@ -1,3 +1,5 @@
+ccflags-y := -Werror
+
 cxl-y				+= main.o file.o irq.o fault.o native.o
 cxl-y				+= context.o sysfs.o debugfs.o pci.o trace.o
 cxl-y				+= vphb.o api.o