Revert "Show no_sim icon when no SIM card is available."

It doesn't look good in the combo RSSI layout, and while we could make 
it look better by adding some padding (like the airplane icon), we haven't
had a no_sim icon since ICS and people are pretty much OK with it.

This reverts commit 2eeacc02.

Bug: 11127588
Change-Id: Ibefd6096171588fcab1e3c5174abda9758cc5f6d