adb: fix apex installation.

Incremental doesn't support apex installation, but we were exiting
instead of returning -1 to fall back to regular installation.

Bug: http://b/151900478
Test: manual
Change-Id: Id27009250090a65fbb45bb65fc39c1799bf1f861
Merged-In: Id27009250090a65fbb45bb65fc39c1799bf1f861
1 file changed