Revert "NFSv4.2: Change the default KConfig value for READ_PLUS"

This reverts commit 7fd461c47c6cfab4ca4d003790ec276209e52978.

Unfortunately, it has come to our attention that there is still a bug
somewhere in the READ_PLUS code that can result in nfsroot systems on
ARM to crash during boot.

Let's do the right thing and revert this change so we don't break
people's nfsroot setups.

Signed-off-by: Anna Schumaker <[e-mail]>
Signed-off-by: Trond Myklebust <[e-mail]>

fs/nfs/Kconfig

···
 config NFS_V4_2_READ_PLUS
 	bool "NFS: Enable support for the NFSv4.2 READ_PLUS operation"
 	depends on NFS_V4_2
-	default y
+	default n
 	help
-	 Choose Y here to enable the use of READ_PLUS over NFS v4.2. READ_PLUS
-	 attempts to improve read performance by compressing out sparse holes
-	 in the file contents.
+	 This is intended for developers only. The READ_PLUS operation has
+	 been shown to have issues under specific conditions and should not
+	 be used in production.