ENGR00151639 - EPDC fb: Memory for PxP workaround buffers may be reduced

ENGR00151639 - EPDC fb: Memory for PxP workaround buffers may be reduced

- This patch changes the way that buffers are allocated and used for the
case where PxP alignment limitations are not met (a copy from the
update source buffer into a temporary buffer before initiating the
PxP processing task is required).  Previously, a buffer was allocated
on a per-update basis, resulting in a large number of copy buffers.  Now,
we allocate just one copy buffer that can be reused any time the PxP
alignment workaround is required.  This is okay because it is assured
that only one PxP transaction can be prepared at a time.

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