sparc32: use PUD rather than PGD to get PMD in srmmu_inherit_prom_mappings()

This is a misprint in the page table traversal in
srmmu_inherit_prom_mappings`() function which accessed a PMD entry using
PGD rather than PUD.

Since sparc32 has only 3 page table levels, the PGD and PUD are
essentially the same and usage of __nocache_fix() removed the type
checking.

Use PUD for the consistency and to avoid breakage because of upcoming
addition of type checking into __nocache_fix().

Fixes: 7235db26 ("sparc32: use pgtable-nopud instead of 4level-fixup")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/mm/srmmu.c

@@ -822,7 +822,7 @@ static void __init srmmu_inherit_prom_mappings(unsigned long start,
 			memset(__nocache_fix(pmdp), 0, SRMMU_PMD_TABLE_SIZE);
 			pud_set(__nocache_fix(pudp), pmdp);
 		}
-		pmdp = pmd_offset(__nocache_fix(pgdp), start);
+		pmdp = pmd_offset(__nocache_fix(pudp), start);
 		if (what == 1) {
 			*(pmd_t *)__nocache_fix(pmdp) = __pmd(probed);
 			start += PMD_SIZE;