e2fsck: check xattr 'system.data' before setting inline_data feature

e2fsck: check xattr 'system.data' before setting inline_data feature

ext2fs_inline_data_size will happy return 0 and set size to
EXT4_MIN_INLINE_DATA_SIZE even when inode doesn't have
xattr 'system.data', a corrupted i_flags could make e2fsck
enable the inline_data on the superblock.

We should only offer to enable inline_data when i_flags is set
and xattr 'system.data' can be found.

Also use correct prompt for PR_1_INLINE_DATA_FEATURE.

Signed-off-by: Li Dongyang <dongyangli@ddn.com>