soc: riscv: privilege: define soc_interrupt_init() as weak symbol

Define soc_interrupt_init as a weak symbol in the common RISC-V
privileged instruction set SoC support.

This allows overriding soc_interrupt_init for SoCs which are not fully
compliant with the RISC-V privileged specification.

Signed-off-by: Henrik Brix Andersen <henrik@brixandersen.dk>

soc/riscv/riscv-privilege/common/soc_common_irq.c

@@ -90,7 +90,7 @@ int arch_irq_is_enabled(unsigned int irq)
 }
 
 #if defined(CONFIG_RISCV_SOC_INTERRUPT_INIT)
-void soc_interrupt_init(void)
+__weak void soc_interrupt_init(void)
 {
 	/* ensure that all interrupts are disabled */
 	(void)irq_lock();