Bramble: fix DumpstateMode validation.

The PROTO mode was added after initial HAL upgrade and is causing VTS
failures due to the way the DumpstateMode param is being validated.

Bug: 150873571
Test: make (no device run VTS, older devices pass with identical change)
Change-Id: Icc4e93c48e65244463db6313de7dee3af098831c
(cherry picked from commit d1ee9061724def9a05c85cb5ec3185368bdf0d03)