fscrypt: remove filesystem specific build config option

In order to have a common code base for fscrypt "post read" processing
for all filesystems which support encryption, this commit removes
filesystem specific build config option (e.g. CONFIG_EXT4_FS_ENCRYPTION)
and replaces it with a build option (i.e. CONFIG_FS_ENCRYPTION) whose
value affects all the filesystems making use of fscrypt.

Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b28e44b..d086f1b1 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1093,7 +1093,7 @@
 	return try_to_free_buffers(page);
 }
 
-#ifdef CONFIG_EXT4_FS_ENCRYPTION
+#ifdef CONFIG_FS_ENCRYPTION
 static int ext4_get_context(struct inode *inode, void *ctx, size_t len)
 {
 	return ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
@@ -1753,7 +1753,7 @@
 		*journal_ioprio =
 			IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, arg);
 	} else if (token == Opt_test_dummy_encryption) {
-#ifdef CONFIG_EXT4_FS_ENCRYPTION
+#ifdef CONFIG_FS_ENCRYPTION
 		sbi->s_mount_flags |= EXT4_MF_TEST_DUMMY_ENCRYPTION;
 		ext4_msg(sb, KERN_WARNING,
 			 "Test dummy encryption mode enabled");
@@ -3889,7 +3889,7 @@
 	sb->s_op = &ext4_sops;
 	sb->s_export_op = &ext4_export_ops;
 	sb->s_xattr = ext4_xattr_handlers;
-#ifdef CONFIG_EXT4_FS_ENCRYPTION
+#ifdef CONFIG_FS_ENCRYPTION
 	sb->s_cop = &ext4_cryptops;
 #endif
 #ifdef CONFIG_QUOTA