capability: fix loops for cap_last_cap()

cap_last_cap() returns the last valid cap (instead of the number of
valid caps). to iterate through all known caps we hence need to use a <=
check, and not a < check like for all other cases. We got this right
usually, but in three cases we did not.

(cherry picked from commit 4a33a02e)
(cherry picked from commit 7f3d4ea4)