LU-10641 e2fsck: avoid write inode attemp in readonly mode

LU-10641 e2fsck: avoid write inode attemp in readonly mode

disconnect_inode() in pass 4 tries to update inode's link count for EA
inodes even in readonly mode. That results in e2fsck -n stop while it
is to continue reporting filesystem inconsistencies.
Move the EA inode's link count update where write access is
guaranteed.

Change-Id: Ie3dcdde160ee9092f21a45fea8f75c4061788072
Signed-off-by: Vladimir Saveliev <c17830@cray.com>
Reviewed-by: Alexandr Boyko <c17825@cray.com>
Reviewed-by: Artem Blagodarenko <c17828@seagate.com>
Cray-bug-id: MRP-4164
Reviewed-on: https://review.whamcloud.com/31226
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>