Tune DTrace 'aframes' for the FBT and profile providers on arm64.

In both cases, too few frames were trimmed, leading to exception handling
or DTrace internals being exposed in stack traces exposed by D's stack()
primitive.

Reviewed by: emaste, andrew
Differential Revision: https://reviews.freebsd.org/D29356

(cherry picked from commit 599fb1d198ec6792ba062114d2589ca9f01a3568)