ext4: add missing save_error_info() to ext4_error()

commit f3fc0210c0fc91900766c995f089c39170e68305 upstream.

The ext4_error() function is missing a call to save_error_info().
Since this is the function which marks the file system as containing
an error, this oversight (which was introduced in 2.6.36) is quite
significant, and should be backported to older stable kernels with
high urgency.

Change-Id: Ifd98e9021037dbf5b84152d8853b214248961794
Reported-by: Ken Sumrall <ksumrall@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: ksumrall@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ken Sumrall <ksumrall@android.com>