Fix === for abstract Reset types (backport #3979) (#3980)

* Fix === for abstract Reset types (#3979)

Previously, the function would infinitely recurse resulting in a stack
overflow.

(cherry picked from commit ea2d1036)

# Conflicts:
#	core/src/main/scala/chisel3/Data.scala

* Resolve backport conflicts

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Co-authored-by: Jack Koenig <koenig@sifive.com>