s3c-fb: fix various null references on framebuffer memory alloc failure

s3c-fb: fix various null references on framebuffer memory alloc failure

The following problems were found in the above situation:

sfb->windows[win] was being assigned at the end of s3c_fb_probe_win only.
This resulted in passing a NULL to s3c_fb_release_win if probe_win
returned early and a memory leak.

dma_free_writecombine does not allow its third argument to be NULL.

fb_dealloc_cmap does not verify whether its argument is not NULL.

Signed-off-by: Pawel Osciak <p.osciak@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: InKi Dae <inki.dae@samsung.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>