fs/qnx6: delete unnecessary checks before brelse()

brelse() tests whether its argument is NULL and then returns immediately. 
Thus remove the tests which are not needed around the shown calls.

Link: https://lkml.kernel.org/r/20220819081819.96347-1-chi.minghao@zte.com.cn


Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Cc: CGEL ZTE <cgel.zte@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minghao Chi <chi.minghao@zte.com.cn>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>