At the end of the first if we see 'vc->gfx.surface = NULL;',
further checking of it is pointless. In the second if, ectx is taken.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Co-developed-by: Linux Verification Center <sdl.qemu@linuxtesting.org>
Signed-off-by: Sergey Mironov <mironov@fintech.ru>
Message-ID: <20231012104448.1251039-1-mironov@fintech.ru>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>