A number of unanswered questions plague “Devara: Part 1,” the fine, but familiar Telugu-language Indian action drama and star vehicle for “RRR” co-lead N.T. Rama Rao Jr. For starters, does this nautical-themed melodrama need to be the first part of a series, and will the heavily foregrounded promise of a sequel leave anyone but NTR’s fans wanting more? It’s hard to know in either case, and not because “Devara: Part 1” doesn’t provide sufficient answers.