staging: lustre: obd: remove unused lmv_readpages()/mdc_readpage()

This patch fixes the following compile error by removing the
dead codes: "error: 'xxx_readpages' defined but not used".
Now that we have md_read_page functionality we can remove
all the *_readpage implementations.

Signed-off-by: Jian Yu <jian.yu@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4669
Reviewed-on: http://review.whamcloud.com/9810


Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>