power: reset: POWER_RESET_TORADEX_EC should depend on ARCH_MXC

The Toradex Embedded Controller is currently only present on Toradex
SMARC iMX8MP and iMX95 SoMs.  Hence add a dependency on ARCH_MXC, to
prevent asking the user about this driver when configuring a kernel
without NXP i.MX SoC family support.

Fixes: 18672fe1 ("power: reset: add Toradex Embedded Controller")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/1ef0beb1e09bf914650f9f9885a33af06772540d.1746536287.git.geert+renesas@glider.be


Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>