adsp-loader: Add support to load adsp fw name

When adsp variant read from fuse registers is not
supported, add support to read the fw name
and load the same.

Change-Id: Icf9aeee8b4c607a6f768f0d73ab0e55d78dc8ac9
Signed-off-by: Aditya Bavanari <abavanar@codeaurora.org>