Allow casts in AsyncReset literal value check (bp #1523) (#1524)

* Allow casts in AsyncReset literal value check (#1523)

Chisel emits all literals as UInts cast to the correct type, make
CheckResets support casts when checking that async reset registers are
reset to literal values.

Co-authored-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>
(cherry picked from commit f8546a7c

)

* Remove intervals test

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