zonefs: Fix zonefs_init_file_inode() return value

Commit 87c9ce3f ("zonefs: Add active seq file accounting") wrongly
changed zonefs_init_file_inode() to always return 0 even if the call to
zonefs_zone_mgmt() fails. Fix this by propagating zonefs_zone_mgmt()
return value as the return value for zonefs_init_file_inode().

Fixes: 87c9ce3f ("zonefs: Add active seq file accounting")
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>