soc: altmode: Remove altmode device name

Remove the device tree property "qcom,altmode-name" and the logic it
feeds as it was meant to help in the cases when there are multiple
altmode devices. Since there is going to be only one altmode device as
per design, this is no longer needed.

Change-Id: Ife15e39becee5f4ff03bdcc56ff62ae812fe2726
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>