ext4: fix incorrect error msg in ext4_ext_insert_index

In function ext4_ext_insert_index when eh_entries of curp is
bigger than eh_max, error messages will be printed out, but the content
is about logical and ei_block, that's incorret.

Signed-off-by: Robin Dong <sanbai@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>