Manifest.permission.READ_EXTERNAL_STORAGE is not needed for API < 16

Summary:
Manifest.permission.READ_EXTERNAL_STORAGE was added in API 16 so older API's do not
have to request this permission

Test Plan:
Install on API < 16 device or emulator
Pair and browse device using dolphin

Reviewers: KDE Connect, albertvaka

Reviewed By: KDE Connect, albertvaka

Subscribers: nicolasfella, kdeconnect

Tags: KDE Connect

Differential Revision: https://phabricator.kde.org/D16613