sbsa_acs_pmu.c offsets are inconsistent

[cdwilde]

REG_PMEVTRYPER is currently set to always have an offset of 4 * mon_inst:
/* Calculate the register offset based on selected monitor */
offset = 4 * mon_inst;

/* Write the received details into PMEVTYPER */
val_mmio_write(base + offset + REG_PMEVTYPER, data);

Later on the file, we calculate the offset based on size:

/* The width of the register PMEVCNTR depends on the size of the largest
implemented counter. if size if PMCFGR.SIZE <= 0b011111, all monitors are
32 bits or smaller else at least one monitor is larger than 32 bits. The
offset is then calculated accordingly. */

if (val_pmu_get_max_monitor_size(node_index) > 0b011111) {
    offset = 8 * mon_inst;
    count = (uint64_t)val_mmio_read(base + offset + REG_PMEVCNTR_H) << 32 |
            val_mmio_read(base + offset + REG_PMEVCNTR_L);
}
else {
    offset = 4 * mon_inst;
    count = val_mmio_read(base + offset + REG_PMEVCNTR);
}

Shouldn't this rule apply to the first offset? We observed failures when we didn't change the offset to 8 * mon_inst.