powerpc/mm: remove unnecessary test in pgtable_cache_init()

pgtable_cache_add() gracefully handles the case when a cache that
size already exists by returning early with the following test:

	if (PGT_CACHE(shift))
		return; /* Already have a cache of this size */

It is then not needed to test the existence of the cache before.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/init-common.c

@@ -111,13 +111,13 @@ void pgtable_cache_init(void)
 {
 	pgtable_cache_add(PGD_INDEX_SIZE);
 
-	if (PMD_CACHE_INDEX && !PGT_CACHE(PMD_CACHE_INDEX))
+	if (PMD_CACHE_INDEX)
 		pgtable_cache_add(PMD_CACHE_INDEX);
 	/*
 	 * In all current configs, when the PUD index exists it's the
 	 * same size as either the pgd or pmd index except with THP enabled
 	 * on book3s 64
 	 */
-	if (PUD_CACHE_INDEX && !PGT_CACHE(PUD_CACHE_INDEX))
+	if (PUD_CACHE_INDEX)
 		pgtable_cache_add(PUD_CACHE_INDEX);
 }