ARM: debug: Use generic 8250 debug_ll for am3517 and am335x

ARM: debug: Use generic 8250 debug_ll for am3517 and am335x

We want to use generic 8250 debug_ll code to get DEBUG_UNCOMPRESS
working and to simplify the code. The old debug_ll code is no longer
needed and the machine ID based detection is no longer used.

Note that for most part there's no need to keep DEBUG_LL enabled.
We now have CONFIG_SERIAL_EARLYCON working very early as long as
the kernel cmdline has "earlycon" in it and the board specific dts
file has chosen configured with with the port using stdout-path.

Cc: Hoeun Ryu <hoeun.ryu@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>