drm/mediatek: Fix CCORR mtk_ctm_s31_32_to_s1_n function issue

if matrixbit is 11,
The range of color matrix is from 0 to (BIT(12) - 1).
Values from 0 to (BIT(11) - 1) represent positive numbers,
values from BIT(11) to (BIT(12) - 1) represent negative numbers.
For example, -1 need converted to 8191.
so convert S31.32 to HW Q2.11 format by drm_color_ctm_s31_32_to_qm_n,
and set int_bits to 2.

Fixes: 738ed4156fba ("drm/mediatek: Add matrix_bits private data for ccorr")
Reviewed-by: AngeloGioacchino Del Regno <[e-mail]>
Signed-off-by: Jay Liu <[e-mail]>
Link: https://patchwork.kernel.org/project/dri-devel/patch/[e-mail]/
Signed-off-by: Chun-Kuang Hu <[e-mail]>

drivers/gpu/drm/mediatek/mtk_disp_ccorr.c

···
 	writel_relaxed(0x0, ccorr->regs + DISP_CCORR_EN);
 }
 
-/* Converts a DRM S31.32 value to the HW S1.n format. */
-static u16 mtk_ctm_s31_32_to_s1_n(u64 in, u32 n)
-{
-	u16 r;
-
-	/* Sign bit. */
-	r = in & BIT_ULL(63) ? BIT(n + 1) : 0;
-
-	if ((in & GENMASK_ULL(62, 33)) > 0) {
-		/* identity value 0x100000000 -> 0x400(mt8183), */
-		/* identity value 0x100000000 -> 0x800(mt8192), */
-		/* if bigger this, set it to max 0x7ff. */
-		r |= GENMASK(n, 0);
-	} else {
-		/* take the n+1 most important bits. */
-		r |= (in >> (32 - n)) & GENMASK(n, 0);
-	}
-
-	return r;
-}
-
 void mtk_ccorr_ctm_set(struct device *dev, struct drm_crtc_state *state)
 {
 	struct mtk_disp_ccorr *ccorr = dev_get_drvdata(dev);
···
 	input = ctm->matrix;
 
 	for (i = 0; i < ARRAY_SIZE(coeffs); i++)
-		coeffs[i] = mtk_ctm_s31_32_to_s1_n(input[i], matrix_bits);
+		coeffs[i] = drm_color_ctm_s31_32_to_qm_n(input[i], 2, matrix_bits);
 
 	mtk_ddp_write(cmdq_pkt, coeffs[0] << 16 | coeffs[1],
 		      &ccorr->cmdq_reg, ccorr->regs, DISP_CCORR_COEF_0);