netfs: Fix wrong #ifdef hiding wait

netfs_writepages_begin() has the wait on the fscache folio conditional on
CONFIG_NETFS_FSCACHE - which doesn't exist.

Fix it to be conditional on CONFIG_FSCACHE instead.

Fixes: 62c3b74 ("netfs: Provide a writepages implementation")
Reported-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-afs@lists.infradead.org
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20240109083257.GK132648@kernel.org/

Author: dhowells

fs/netfs/buffered_write.c

@@ -1076,7 +1076,7 @@ static ssize_t netfs_writepages_begin(struct address_space *mapping,
 		folio_unlock(folio);
 		if (wbc->sync_mode != WB_SYNC_NONE) {
 			folio_wait_writeback(folio);
-#ifdef CONFIG_NETFS_FSCACHE
+#ifdef CONFIG_FSCACHE
 			folio_wait_fscache(folio);
 #endif
 			goto lock_again;