Fix the bug that camera can't open again after disconnected

Reproduce steps:
1. Open android default camera
2. Open chrome camera app
3. Close chrome camera app
4. Android camera app is disconnected. Close it.
5. Open android camera app again. It can't open camera anymore.

The root cause is that camera state is set to invalid after getting
an exception in step 4. We should not invalidate the camera.

BUG=35411023
TEST=In samus, verify that camera can be opened after the above steps

Change-Id: I63bcc3587d1c7970c1bad8bffa628fa579f831ef
(cherry picked from commit a822d5c3528473582de6b2f9db0bee3ea2a18190)