LU-9091 procfs: remove old string parsing routines

LU-9091 procfs: remove old string parsing routines

Remove the llprocfs_str_with_units_to_s64(), lu_str_to_s64(),
llprocfs_str_with_units_to_u64(), and lu_str_to_u64() functions.
All new code should use sysfs_memparse() to parse sizes from
userspace.

Mark patch forbuildonly so that it does not land before we have
a chance to remove any patches with users of these functions.

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I6dc321e60eb587ef25652f4b5ae8fa478d3ebbe5
Reviewed-on: https://review.whamcloud.com/37275
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>