stm32_iwdg: remove panic function from watchdog irq handler

This commit removes the panic function to avoid the following
error message when doing a watchdog reset.

E/TC:1 Panic 'Watchdog' at core/drivers/stm32_iwdg.c:193 <stm32_iwdg_it_handler>
E/TC:1 TEE load address @ 0x82000000
E/TC:1 Call stack:
E/TC:1 0x82008230
E/TC:1 0x82034b88
E/TC:1 0x820193c8
E/TC:1 0x82033abc
E/TC:1 0x82013504
E/TC:1 0x820017dc

https://onedigi.atlassian.net/browse/DEL-9231

Signed-off-by: Mike Engel <[email protected]>

core/drivers/stm32_iwdg.c

@@ -190,8 +190,6 @@ static enum itr_return stm32_iwdg_it_handler(struct itr_handler *h)
 	else
 		io_setbits32(iwdg_base + IWDG_EWCR_OFFSET, IWDG_EWCR_EWIC);
 
-	panic("Watchdog");
-
 	return ITRR_HANDLED;
 }