powerpc/papr_scm: Make some symbols static

The sparse tool complains as follows:

arch/powerpc/platforms/pseries/papr_scm.c:97:1: warning:
 symbol 'papr_nd_regions' was not declared. Should it be static?
arch/powerpc/platforms/pseries/papr_scm.c:98:1: warning:
 symbol 'papr_ndr_lock' was not declared. Should it be static?

Those variables are not used outside of papr_scm.c, so this
commit marks them static.

Fixes: 85343a8d ("powerpc/papr/scm: Add bad memory ranges to nvdimm bad ranges")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200725091949.75234-1-weiyongjun1@huawei.com

arch/powerpc/platforms/pseries/papr_scm.c

@@ -94,8 +94,8 @@ struct papr_scm_priv {
 	u64 health_bitmap;
 };
 
-LIST_HEAD(papr_nd_regions);
-DEFINE_MUTEX(papr_ndr_lock);
+static LIST_HEAD(papr_nd_regions);
+static DEFINE_MUTEX(papr_ndr_lock);
 
 static int drc_pmem_bind(struct papr_scm_priv *p)
 {