This change fixes the checkpatch warning described in this commit
commit cbacb5ab ("docs: printk-formats: Stop encouraging use of
  unnecessary %h[xudi] and %hh[xudi]")

Standard integer promotion is already done and %hx and %hhx is useless
so do not encourage the use of %hh[xudi] or %h[xudi].

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210127222344.2445641-1-trix@redhat.com