fs: drop unused fput_atomic definition

commit d7065da0 ("get rid of the magic around f_count in aio") added
fput_atomic to include/linux/fs.h, motivated by its use in __aio_put_req()
in fs/aio.c.

Later, commit 3ffa3c0e ("aio: now fput() is OK from interrupt context;
get rid of manual delayed __fput()") removed the only use of fput_atomic
in __aio_put_req(), but did not remove the since then unused fput_atomic
definition in include/linux/fs.h.

We curate this now and finally remove the unused definition.

This issue was identified during a code review due to a coccinelle warning
from the atomic_as_refcounter.cocci rule pointing to the use of atomic_t
in fput_atomic.
Suggested-by: Krystian Radlak <kradlak@exida.com>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/fs.h

@@ -969,7 +969,6 @@ static inline struct file *get_file(struct file *f)
 #define get_file_rcu_many(x, cnt)	\
 	atomic_long_add_unless(&(x)->f_count, (cnt), 0)
 #define get_file_rcu(x) get_file_rcu_many((x), 1)
-#define fput_atomic(x)	atomic_long_add_unless(&(x)->f_count, -1, 1)
 #define file_count(x)	atomic_long_read(&(x)->f_count)
 
 #define	MAX_NON_LFS	((1UL<<31) - 1)