drm/mgag200: deal with bo reserve fail in dirty update path

drm/mgag200: deal with bo reserve fail in dirty update path

commit 641719599528d806e00de8ae8c8453361266a312 upstream.

On F19 testing, it was noticed we get a lot of errors in dmesg
about being unable to reserve the buffer when plymouth starts,
this is due to the buffer being in the process of migrating,
so it makes sense we can't reserve it.

In order to deal with it, this adds delayed updates for the dirty
updates, when the bo is unreservable, in the normal console case
this shouldn't ever happen, its just when plymouth or X is
pushing the console bo to system memory.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>