LU-9399 llite: register mountpoint before process llog

LU-9399 llite: register mountpoint before process llog

In ll_fill_super(), lprocfs_ll_register_mountpoint() should be
called before lustre_process_log(), otherwise the directory
/proc/fs/lustre/llite/* can't be created in time and the params
"llite.*.*" won't be set correctly.

Also, this patch adds sbi->ll_xattr_cache_set to mark the flag
LL_SBI_XATTR_CACHE already set during lustre_process_log(),
in case that it will be overwritten in client_common_fill_super().

conf-sanity.sh test_76d is added to verify this fix.

Signed-off-by: Emoly Liu <emoly.liu@intel.com>
Change-Id: Ie1b4d2ef23bbe48a22d48f92f7d4efe64042eec4
Reviewed-on: https://review.whamcloud.com/27241
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>