epjitsu: read page_width pixels from scanner

This commit fixes a regression introduced in 1.0.25 for ADF scanners:
the scanning page-width was always set to a fixed value,
ignoring the page-width provided by the frontend.

This commit restores the behaviour that allows changing the page-width.

Signed-off-by: Peter Marschall <peter@adpm.de>

backend/epjitsu.c

@@ -2180,7 +2180,7 @@ change_params(struct scanner *s)
       /* adf with specified paper size */
       s->front.height = SCANNER_UNIT_TO_PIX(s->page_height, s->front.y_res);
     }
-    s->front.width_pix = s->block_img.width_pix;
+    s->front.width_pix = SCANNER_UNIT_TO_PIX(s->page_width, s->resolution * img_heads);
     s->front.x_start_offset = (s->block_xfr.image->width_pix - s->front.width_pix)/2;
     switch (s->mode) {
       case MODE_COLOR: