arm: Fix typos in comments

The width register has been set to clz(w)-24, not the other way
around. And the 32 bit prep function has got the h parameter in
r4, not in r5.
21 jobs for master in 6 minutes and 6 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Style
passed style-check #268965
amd64 debian

00:00:23

 
  Build
passed build-debian #268966
amd64 debian

00:00:41

passed build-debian-aarch64 #268974
debian aarch64

00:01:33

passed build-debian-aarch64-clang-5 #268975
debian aarch64

00:01:05

passed build-debian-armv7 #268978
debian armv7

00:01:42

passed build-debian-armv7-clang-5 #268979
debian armv7

00:01:20

passed build-debian-static #268967
amd64 debian

00:00:41

passed build-debian-werror #268977
debian aarch64

00:00:35

passed build-debian32 #268968
amd64 debian

00:00:39

passed build-macos #268976
macos

00:00:37

passed build-ubuntu-snap #268980
amd64 debian

00:01:02

passed build-win-arm32 #268972
amd64 debian

00:00:33

passed build-win-arm64 #268973
amd64 debian

00:00:34

passed build-win32 #268969
amd64 debian

00:00:42

passed build-win32-unaligned-stack #268970
amd64 debian

00:00:46

passed build-win64 #268971
debian amd64

00:00:47

 
  Test
passed test-debian #268981
amd64 debian

00:00:49

passed test-debian-asan #268982
amd64 debian

00:02:20

passed test-debian-msan #268983
amd64 debian

00:01:06

passed test-debian-ubsan #268984
amd64 debian

00:01:31

passed test-win64 #268985
amd64 debian

00:00:58