powerpc/papr_scm: Use depend instead of select

Making PAPR_SCM select LIBNVDIMM results in circular dependencies in
Kconfig when another symbol depends on it. Fix this by replacing the
select with a depends.

Fixes: b5beae5e224f ("powerpc/pseries: Add driver for PAPR SCM regions")
Reported-by: Alastair D'Silva <alastair@d-silva.org>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/pseries/Kconfig

@@ -140,8 +140,7 @@ config IBMEBUS
 	  Bus device driver for GX bus based adapters.
 
 config PAPR_SCM
-	depends on PPC_PSERIES && MEMORY_HOTPLUG
-	select LIBNVDIMM
+	depends on PPC_PSERIES && MEMORY_HOTPLUG && LIBNVDIMM
 	tristate "Support for the PAPR Storage Class Memory interface"
 	help
 	  Enable access to hypervisor provided storage class memory.