mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage

Mostly direct substitution with occasional adjustment or removing
outdated comments.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index 1b45694..7ff6fcf 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -37,7 +37,7 @@
 {
 	unsigned len = le16_to_cpu(dlen);
 
-#if (PAGE_CACHE_SIZE >= 65536)
+#if (PAGE_SIZE >= 65536)
 	if (len == EXT2_MAX_REC_LEN)
 		return 1 << 16;
 #endif
@@ -46,7 +46,7 @@
 
 static inline __le16 ext2_rec_len_to_disk(unsigned len)
 {
-#if (PAGE_CACHE_SIZE >= 65536)
+#if (PAGE_SIZE >= 65536)
 	if (len == (1 << 16))
 		return cpu_to_le16(EXT2_MAX_REC_LEN);
 	else