powerpc/pseries/lparcfg: Fix display of Maximum Memory

Correct overflow problem in calculation and display of Maximum Memory
value to syscfg.
Signed-off-by: Michael Bringmann <mwb@linux.ibm.com>
[mpe: Only n_lmbs needs casting to unsigned long]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/5577aef8-1d5a-ca95-ff0a-9c7b5977e5bf@linux.ibm.com

arch/powerpc/platforms/pseries/lparcfg.c

@@ -435,10 +435,10 @@ static void maxmem_data(struct seq_file *m)
 {
 	unsigned long maxmem = 0;
 
-	maxmem += drmem_info->n_lmbs * drmem_info->lmb_size;
+	maxmem += (unsigned long)drmem_info->n_lmbs * drmem_info->lmb_size;
 	maxmem += hugetlb_total_pages() * PAGE_SIZE;
 
-	seq_printf(m, "MaxMem=%ld\n", maxmem);
+	seq_printf(m, "MaxMem=%lu\n", maxmem);
 }
 
 static int pseries_lparcfg_data(struct seq_file *m, void *v)