f2fs: fix spelling in ABI documentation

Correct spelling problems as identified by codespell.

Fixes: 9e615dbb ("f2fs: add missing description for ipu_policy node")
Fixes: b2e4a2b3 ("f2fs: expose discard related parameters in sysfs")
Fixes: 846ae671 ("f2fs: expose extension_list sysfs entry")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Chao Yu <chao@kernel.org>
Cc: linux-f2fs-devel@lists.sourceforge.net
Cc: Yangtao Li <frank.li@vivo.com>
Cc: Konstantin Vyshetsky <vkon@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -54,9 +54,9 @@ Description:	Controls the in-place-update policy.
 		0x00  DISABLE         disable IPU(=default option in LFS mode)
 		0x01  FORCE           all the time
 		0x02  SSR             if SSR mode is activated
-		0x04  UTIL            if FS utilization is over threashold
+		0x04  UTIL            if FS utilization is over threshold
 		0x08  SSR_UTIL        if SSR mode is activated and FS utilization is over
-		                      threashold
+		                      threshold
 		0x10  FSYNC           activated in fsync path only for high performance
 		                      flash storages. IPU will be triggered only if the
 		                      # of dirty pages over min_fsync_blocks.
@@ -117,7 +117,7 @@ Date:		December 2021
 Contact:	"Konstantin Vyshetsky" <vkon@google.com>
 Description:	Controls the number of discards a thread will issue at a time.
 		Higher number will allow the discard thread to finish its work
-		faster, at the cost of higher latency for incomming I/O.
+		faster, at the cost of higher latency for incoming I/O.
 
 What:		/sys/fs/f2fs/<disk>/min_discard_issue_time
 Date:		December 2021
@@ -334,7 +334,7 @@ Description:	This indicates how many GC can be failed for the pinned
 		state. 2048 trials is set by default.
 
 What:		/sys/fs/f2fs/<disk>/extension_list
-Date:		Feburary 2018
+Date:		February 2018
 Contact:	"Chao Yu" <yuchao0@huawei.com>
 Description:	Used to control configure extension list:
 		- Query: cat /sys/fs/f2fs/<disk>/extension_list