DataUsageSummary: fix mobile data usage display for GSM devices with no number

Some providers don't write phone number onto SIM card causing the
phone number check introduced in the partially reverted commit to fail.
Re-introduce the original check with the "or" condition.

This partially reverts commit 4c51b45355b9d6fed973f946738bf455a8b7c9ea.

Change-Id: I69a65a1a421dcdf168c3d0afeb7110cb97790034