Use normal case for Carrier Text in LockScreen.

For example: Nexus 6 on Verizon shows "Verizon Wireless" not
"VERIZON WIRELESS" on the lockscreen.

Taken from http://review.cyanogenmod.org/#/c/82489/

Change-Id: Idc9913aeaa9256da00218cd7fc0927120120ac48