at91: video: atmel_hlcdfb.c: fix bad timing configuration

The right correspondance between LCD margins and LCD timings is:
    * upper margin -> vertical back porch
    * lower margin -> vertical front porch
    * left  margin -> horizontal back porch
    * right margin -> horizontal front porch

Signed-off-by: Josh Wu <josh.wu@atmel.com>
1 file changed