watchdog: qcom: add option for standalone watchdog not in timer block

Commit 0dfd582e ("watchdog: qcom: use timer devicetree
binding") moved to use the watchdog as a subset timer
register block. Some devices have the watchdog completely
standalone with slightly different register offsets as
well so let's account for the differences here.

The existing "kpss-standalone" compatible string doesn't
make it entirely clear exactly what the device is so
rename to "kpss-wdt" to reflect watchdog timer
functionality. Also update ipq4019 DTS with an SoC
specific compatible.

Signed-off-by: Matthew McClintock <mmcclint@codeaurora.org>
Signed-off-by: Thomas Pedersen <twp@codeaurora.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>