drm/bridge: sii902x: pixel clock unit is 10kHz instead of 1kHz

The pixel clock unit in the first two registers (0x00 and 0x01) of
sii9022 is 10kHz, not 1kHz as in struct drm_display_mode. Division by
10 fixes the issue.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1a2a8eae0b9d6333e7a5841026bf7fd65c9ccd09.1558964241.git.jsarha@ti.com