writeback: cleanup writeback_single_inode()
writeback: cleanup writeback_single_inode()

Make the if-else straight in writeback_single_inode().
No behavior change.

Cc: Jan Kara <596727c8a0ea4db3ba2ceceedccbacd3d7b371b8@suse.cz>
Cc: Michael Rubin <4fde2c96bbb2b79984d097dee9168089855814c5@google.com>
Cc: Peter Zijlstra <3fddac958924aef220f202ca567388ddab3f14a8@infradead.org>
Signed-off-by: Fengguang Wu <f25caf39e3e90f2a28a0f6211af92081109b663e@mail.ustc.edu.cn>
Signed-off-by: Jens Axboe <165ab144a3ccfd9429d5c6466b275f24fafdb114@oracle.com>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas