gpu: drm: mgag200: mgag200_main:- Handle error from pci_iomap

BugLink: http://bugs.launchpad.net/bugs/1744639

[ Upstream commit 4b0ea93f ]

Here, pci_iomap can fail, handle this case and return -ENOMEM.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1483443027-13444-1-git-send-email-arvind.yadav.cs@gmail.comSigned-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/gpu/drm/mgag200/mgag200_main.c

@@ -145,6 +145,8 @@ static int mga_vram_init(struct mga_device *mdev)
 	}
 
 	mem = pci_iomap(mdev->dev->pdev, 0, 0);
+	if (!mem)
+		return -ENOMEM;
 
 	mdev->mc.vram_size = mga_probe_vram(mdev, mem);