imx: imx8m: Don't use the addr parameter of reset_cpu

imx: imx8m: Don't use the addr parameter of reset_cpu

imx8m has the only implementation of `reset_cpu` which does not ignore
the addr parameter and instead gives it some meaning as the base address
of watchdog registers.  This breaks convention with the rest of U-Boot
where the parameter is ignored and callers are passing in 0.

Fixes: d2041725e84b ("imx8m: restrict reset_cpu")
Co-Authored-by: Harald Seiler <hws@denx.de>
Signed-off-by: Claudius Heine <ch@denx.de>
Signed-off-by: Harald Seiler <hws@denx.de>
Reviewed-by: Marek Vasut <marex@denx.de>