LU-8259 osd-ldiskfs update all *_seq_write() to use "const char __user *buffer"

LU-8259 osd-ldiskfs update all *_seq_write() to use "const char __user *buffer"

All *_seq_write functions in lustre/osd-ldiskfs/osd_lproc.c declare
buffer as "const char *buffer" and should use "const char __user *buffer"
instead.

This patch takes care of this change.

Change-Id: Ida44679f721a37cf71f327a6f00f3f8857ba0376
Signed-off-by: Parinay Kondekar <parinay.kondekar@seagate.com>
Reviewed-on: http://review.whamcloud.com/20887
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>