bin/droid script: fix wierd mkdir error on my device

Here's the error:
    adb: error: failed to copy '...' to '...':
    remote secure_mkdirs failed: Operation not permitted

I also cleaned up the script.

No-Try: true
Change-Id: Ie2dec7b42eaf2a19475cdd0a04074f8bec47b2fb
Reviewed-on: https://skia-review.googlesource.com/148906
Auto-Submit: Hal Canary <halcanary@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
1 file changed