lib: sbi: Remove regs paramter of sbi_irqchip_process()

The irqchip handlers will typically not need pointer to trap registers
so remove regs parameter of sbi_irqchip_process().

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Tested-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Clément Léger <cleger@rivosinc.com>