Fix signed/unsigned arithmetic bug during scrolling

[lhecker]

ed27737 contains a regression where (pseudocode)

unsigned long ulActualDelta;
short ScreenInfo.WheelDelta;
delta *= (ScreenInfo.WheelDelta / (short)ulActualDelta);
//                                ^^^^^^^

was changed to

delta *= (ScreenInfo.WheelDelta / ulActualDelta);

Due to ulActualDelta being unsigned, the new code casts the signed integer
to a unsigned one first, before doing the division. This causes scrolling
downwards (WheelDelta is negative) to appear as a large positive delta.

PR Checklist

• Closes Scroll wheel no longer works correctly in OpenConsole #13253
• I work here

Validation Steps Performed

• Scrolling up/down works in OpenConsole again ✅

[ghost]

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[DHowett]

@msftbot merge this in 1 minute

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