soc: arm: move z_clearfaults() in kernel_arch_init()

In kernel_arch_init() we initialize the ARM core (interrupt
setup, fault init, etc.) so we can also move z_clearfaults()
in the same function and skip invoking it in the SoC init
functions.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>

soc/arm/st_stm32/stm32l4/soc.c

@@ -31,8 +31,6 @@ static int stm32l4_init(struct device *arg)
 
 	key = irq_lock();
 
-	z_clearfaults();
-
 	/* Install default handler that simply resets the CPU
 	 * if configured in the kernel, NOP otherwise
 	 */