Update EIP-1108 to reflect Final status (ethereum#2295)

Since the Istanbul meta-EIP has EIP-1108 listed for the hardfork and
the implementation tracker lists everyone as having merged, this EIP
seems reasonable to move to Final status.

EIPS/eip-1108.md

@@ -3,7 +3,7 @@ eip: 1108
 title: Reduce alt_bn128 precompile gas costs
 author: Antonio Salazar Cardozo (@shadowfiend), Zachary Williamson (@zac-williamson)
 discussions-to: https://ethereum-magicians.org/t/eip-1108-reduce-alt-bn128-precompile-gas-costs/3206
-status: Draft
+status: Final
 type: Standards Track
 category: Core
 created: 2018-05-21