update exploder+pexarria5 top designs (scu is broken by this commit)

This commit tracks the changes made to the altera_reset/phase cores.

For pexarria5 we make these changes:
  - attach two LVDS inputs to the TLU
  - clean up USB reset
  - split altera_butis into altera_phase+butis
  - update altera_reset hooks

For exploder we make these changes:
  - switch clock networking to mirror arria5
  - use altera_reset to power-up
  - clean-up USB reset
  - split altera_butis into altera_phase+butis
  - logic lock GXB TX path