ext4: remove unnecessary conditionals

iput() has already handled null and non-null parameter, so it is no
need to use if().

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Lv Ruyi <lv.ruyi@zte.com.cn>
Link: https://lore.kernel.org/r/20220411032337.2517465-1-lv.ruyi@zte.com.cn


Signed-off-by: Theodore Ts'o <tytso@mit.edu>