watchdog: orion: Add support for Armada 370 and Armada XP SoC

Using the added infrastructure for handling SoC differences,
this commit adds support for the watchdog controller available
in Armada 370 and Armada XP SoCs.

Also, and because the AXP clock initialization uses of_clk_get_by_name,
this commit changes the orion clock initialization to use clk_get() and
adds a proper clk_put() on the common exit/error paths.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Acked-by: Wim Van Sebroeck <wim@iguana.be>
Tested-By: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>