media: sun4i-csi: Fix data sampling polarity handling

The CLK_POL field specifies whether data is sampled on the falling or
rising edge of PCLK, not whether the data lines are active high or low.
Evidence of this can be found in the timing diagram labeled "horizontal
size setting and pixel clock timing".

Fix the setting by checking the correct flag, V4L2_MBUS_PCLK_SAMPLE_RISING.
While at it, reorder the three polarity flag checks so HSYNC and VSYNC
are grouped together.

Fixes: 577bbf23 ("media: sunxi: Add A10 CSI driver")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>