[PW5 MTK] Fix swipe animations with a tiny refresh area

[yparitcher]

koreader/koreader#9245 koreader/koreader-base/pull/1494

The simplest way to trigger this is fbink -K direction=LEFT,steps=12 -s width=11

The MTK Driver will crash if given a area smaller than the number of steps. If direction is L/R and w is smaller or if it is U/D and h is smaller Being as one generally will only want animations on a larger area, and I am too lazy to test for direction, disable animations when w or h is less than steps.

I did not add any error handling etc, feel free to spice it up.

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This change is 

[yparitcher]

Not tested

[NiLuJe]

Oh, makes sense, thanks for the detective work ;).

[NiLuJe]

Thanks!