ENGR00152681 - EPDC fb: Updates may be shifted right by 1 column

ENGR00152681 - EPDC fb: Updates may be shifted right by 1 column

- Fixed PxP input left coordinate value.  Was previously being incorrectly
computed such that the value would be incorrect when using 16bpp RGB and an
X coordinate that is offset from 4-pixel alignment by 1 (e.g. x=1, x=5).
The resulting effect was that updates meeting this criteria would be
drawn to the EPD panel shifted to the right by 1 pixel.

Signed-off-by: Danny Nold <dannynold@freescale.com>