Cleanup fs_getline from fs_mgr

Since getline is included in bionic, fs_mgr can use this version instead of
the one defined internally by fs_getline.

Replace fs_getline with getline.

Change-Id: I49b53d639bd995f051256fb7573ff6ab45d9c36d
Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Fix fstab memory leak

When reading the fstab config file fails, fstab memory is not freed.
When fstab structure is no longer needed, only half of it is freed.

Free fstab memory in all cases (error or when it is no longer needed).

Change-Id: Ib0758a5aaa69505285bf64143632986a2dbbdccb
Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>