m7att: Correct manufacturer, htc to HTC

Change htc for m7att manufacter to HTC to make the string look cleaner
in Android Device Manager and Google Play Store (commonly used by users),
as well as any app that reads ro.product.manufacturer from build.prop.
Also, HTC styles their name in print as being uppercase and generally have
it uppercase in their stock ROMs.

Change-Id: I2c9c341f3c5c7f1a7bb8b145d86e5471a9a9d652