Documentation: block/diskstats: update function names

__make_request() and end_that_request_last() do no longer exist. Replace
them with the current call-site.

Signed-off-by: Naohiro Aota <[e-mail]>
Reviewed-by: Chaitanya Kulkarni <[e-mail]>
Reviwed-by: Jens Axboe <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/admin-guide/iostats.rst

···
 
 Field  4 -- # of milliseconds spent reading (unsigned int)
     This is the total number of milliseconds spent by all reads (as
-    measured from __make_request() to end_that_request_last()).
+    measured from blk_mq_alloc_request() to __blk_mq_end_request()).
 
 Field  5 -- # of writes completed (unsigned long)
     This is the total number of writes completed successfully.
···
 
 Field  8 -- # of milliseconds spent writing (unsigned int)
     This is the total number of milliseconds spent by all writes (as
-    measured from __make_request() to end_that_request_last()).
+    measured from blk_mq_alloc_request() to __blk_mq_end_request()).
 
 Field  9 -- # of I/Os currently in progress (unsigned int)
     The only field that should go to zero. Incremented as requests are
···
 
 Field 15 -- # of milliseconds spent discarding (unsigned int)
     This is the total number of milliseconds spent by all discards (as
-    measured from __make_request() to end_that_request_last()).
+    measured from blk_mq_alloc_request() to __blk_mq_end_request()).
 
 Field 16 -- # of flush requests completed
     This is the total number of flush requests completed successfully.