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].

Link: https://lore.kernel.org/r/20210124150916.1920434-1-trix@redhat.comSigned-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>