Add suppression for non-zero index access in logd

cppcheck generates a warning about the non-zero index access in the
toCpu function. This is expected behavior so the warning has been
suppressed.

Change-Id: I852ca8f0b987215156edb826e643e3844e35049d
Signed-off-by: Mikael Olsson <mikael.olsson@arm.com>