[system][bt] fix -Wc99-designator

Fixes the observed warning:
error: mixture of designated and non-designated initializers in the same
initializer list is a C99 extension [-Werror,-Wc99-designator]

Bug: 143622397
Test: mm
Change-Id: I5835e729979d8fb3f928821d4cd6aff693b14ab7
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>