video: deferred io cleanup fix for sh_mobile_lcdcfb

Fix deferred io cleanup patch in the sh_mobile_lcdcfb driver.

If probe() fails early the sh_mobile_lcdc_stop() function will
be called to clean up deferred io. This patch modifies the
code to only call fb_deferred_io_cleanup() after deferred io
has been initialized.

With this patch applied we no longer hit BUG_ON() inside
fb_deferred_io_cleanup(). Triggers on a Migo-R with the
SYS QVGA panel board unmounted.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>