video: Adjust rotated console to start at right edge

video: Adjust rotated console to start at right edge

At present when the console is rotated 180 degrees it starts almost a
whole character to the left of the right edge (typically 7 pixels with
an 8-pixel-wide font). On a display which aligns with the font width,
this just wastes space. On a display that does not this can result in
x_frac going negative for the final character (the one on the left
side) and the overflow -EAGAIN check at the start of the function
failing.

Change the function to start at the rightmost pixel to fix these
problems.

Signed-off-by: Simon Glass <[email protected]>
Reviewed-by: Anatolij Gustschin <[email protected]>
Tested-by: Bin Meng <[email protected]>