powerpc/lmb-size: Use addr #size-cells value when fetching lmb-size

Make it consistent with other usages.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201007114836.282468-5-aneesh.kumar@linux.ibm.com
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 78c5afe..f8e9eb4 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -498,7 +498,7 @@ static int __init probe_memory_block_size(unsigned long node, const char *uname,
 					  depth, void *data)
 {
 	unsigned long *mem_block_size = (unsigned long *)data;
-	const __be64 *prop;
+	const __be32 *prop;
 	int len;
 
 	if (depth != 1)
@@ -508,13 +508,14 @@ static int __init probe_memory_block_size(unsigned long node, const char *uname,
 		return 0;
 
 	prop = of_get_flat_dt_prop(node, "ibm,lmb-size", &len);
-	if (!prop || len < sizeof(__be64))
+
+	if (!prop || len < dt_root_size_cells * sizeof(__be32))
 		/*
 		 * Nothing in the device tree
 		 */
 		*mem_block_size = MIN_MEMORY_BLOCK_SIZE;
 	else
-		*mem_block_size = be64_to_cpup(prop);
+		*mem_block_size = of_read_number(prop, dt_root_size_cells);
 	return 1;
 }