These are never modified, so make them const to allow the compiler to
put them in read-only memory.

Link: https://lore.kernel.org/r/20200906230452.33410-4-rikard.falkeborn@gmail.comSigned-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>