LU-15542 osd-ldiskfs: exclude EA inode from processing

LU-15542 osd-ldiskfs: exclude EA inode from processing

EA inode is ldiskfs internal object and this should be
excluded at any osd access.
Panic fixed by this change because iterator will return
an error when tries to access to the ea inode.

osd_ea_fid_get()) Process leaving (rc=18446744073709551614 : -2
osd_it_ea_rec()) Process leaving (rc=18446744073709551614 : -2)
osd_it_ea_next()) Process entered

HPe-bug-id: LUS-10683
Signed-off-by: Alexey Lyashkov <alexey.lyashkov@hpe.com>
Change-Id: I73e5325721ae28ea380e9d216c6c6cf7fa0ac4ea
Reviewed-on: https://review.whamcloud.com/46486
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andrew Perepechko <andrew.perepechko@hpe.com>
Reviewed-by: Alexander Zarochentsev <alexander.zarochentsev@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>