LU-11215 libe2p: add large_xattr as an alias of ea_inode

LU-11215 libe2p: add large_xattr as an alias of ea_inode

The upstream version of large xattr suppport doesn't
add "large_xattr" as a feature name, but it's still
used by our test scripts.

e2fsprogs commit:6a081f6d2a5cff0f5a077065aab39901d54bfb61

Change-Id: I48d7ac54b2b2ad252c404050bc4c3d9527865107
Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-on: https://review.whamcloud.com/32932
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>