ext4: report real fs size after failed resize

Currently when the file system resize using ext4_resize_fs() fails it
will report into log that "resized filesystem to <requested block
count>".  However this may not be true in the case of failure.  Use the
current block count as returned by ext4_blocks_count() to report the
block count.

Additionally, report a warning that "error occurred during file system
resize"

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>