Clean-up: use sizeof instead of repeating string length constant

Looking into a number of coverity reports (false positives), I
identified a number of sites which use the maximal symbol length
constant when the actual size of an array can be used. This will prevent
mismatches in the future should the array sizes change.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ia74f43d3871fdce60affbde068401b58c84b09ad