Fix Flail/Reversal BP modifier in Gen 2-3

[Karthik99999]

https://www.smogon.com/forums/threads/gen-3-reversal-flail.3743660/

[baskuit]

I was about to prepare my own PR until I found this. This is correct. My change would have use <= 4 instead of < 5 but I see no issue.

This code was taken from the emerald decomp

u8 GetScaledHPFraction(s16 hp, s16 maxhp, u8 scale)
{
    u8 result = hp * scale / maxhp;

    if (result == 0 && hp > 0)
        return 1;

    return result;
}
static void Cmd_remaininghptopower(void)
{
    s32 i;
    s32 hpFraction = GetScaledHPFraction(gBattleMons[gBattlerAttacker].hp, gBattleMons[gBattlerAttacker].maxHP, 48);

    for (i = 0; i < (s32) sizeof(sFlailHpScaleToPowerTable); i += 2)
    {
        if (hpFraction <= sFlailHpScaleToPowerTable[i])
            break;
    }

    gDynamicBasePower = sFlailHpScaleToPowerTable[i + 1];
    gBattlescriptCurrInstr++;
}
static const u8 sFlailHpScaleToPowerTable[] =
{
    1, 200,
    4, 150,
    9, 100,
    16, 80,
    32, 40,
    48, 20
};

The code can be found here https://github.com/pret/pokeemerald/blob/18f84b78f2d1a8669753fa586836fca06036c790/src/battle_script_commands.c#L8246

[DaWoblefet]

Thanks Karthik!