kmp204x: set CPU watchdog reset reason flag

Check the core timer status register (TSR) for watchdog reset,
and and set the QRIO's reset reason flag REASON1[0] accordingly.

This allows the appliction SW to identify the cpu watchdog as a
reset reason, by setting the REASON1[0] flag in the QRIO.

Signed-off-by: Rainer Boschung <rainer.boschung@keymile.com>
Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
Reviewed-by: York Sun <yorksun@freescale.com>