libhwbinder: missing /dev/hwbinder is not a fatal error

b/31458381
b/31240290
causes b/31715232
Test: pass

Change-Id: I9b6b9e8ce5c04e4707f12cf623718a037c35596a
Signed-off-by: Iliyan Malchev <malchev@google.com>
1 file changed