[rtl872x] correctly handle SecureFault

[avtolstoy]

See [SC121377]

[YutingYou]

Tested with below app, secure fault handler in VTOR_NS can be handled.

void setup() {
    uint32_t *test_ptr = (uint32_t *)0x1007EFFC;    // SecureFault
    // uint32_t *test_ptr = (uint32_t *)0x0;        // BusFault
    volatile uint32_t test_value = 0;
    test_value = *test_ptr;
}