linux-phytec-ti

arm: phytec: add support for AM5749 and refactor files

In the process of adding support for AM5749, more
granularity was required to separate the features of
am571x, am572x, and am574x silicon from one another.

The common files are more limited in scope, with am572x
and am574x having more in common, and am571x having
mostly its own files.

Signed-off-by: Russell Robinson <rrobinson@phytec.com>
Signed-off-by: Matt McKee <mmckee@phytec.com>