ARM: qcom: add description of KPSS WDT for IPQ8064

Add the watchdog related entries to the Krait Processor Sub-system
(KPSS) timer IPQ8064 devicetree section. Also, add a fixed-clock
description of SLEEP_CLK, which will do for now.

Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>