vfio-dev/mdpy-fb: Use fbdev I/O helpers

Set struct fb_ops and with FB_DEFAULT_IOMEM_OPS, fbdev's initializer
for I/O memory. Sets the callbacks to the cfb_ and fb_io_ functions.
Select the correct modules with Kconfig's FB_IOMEM_HELPERS token.

The macro and token set the currently selected values, so there is
no functional change.

v3:
	* use _IOMEM_ in commit message
v2:
	* updated to use _IOMEM_ tokens
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Helge Deller <deller@gmx.de>
Cc: Kirti Wankhede <kwankhede@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230803184034.6456-48-tzimmermann@suse.de

samples/Kconfig

@@ -210,9 +210,7 @@ config SAMPLE_VFIO_MDEV_MDPY
 config SAMPLE_VFIO_MDEV_MDPY_FB
 	tristate "Build VFIO mdpy example guest fbdev driver"
 	depends on FB
-	select FB_CFB_FILLRECT
-	select FB_CFB_COPYAREA
-	select FB_CFB_IMAGEBLIT
+	select FB_IOMEM_HELPERS
 	help
 	  Guest fbdev driver for the virtual display sample driver.
 

samples/vfio-mdev/mdpy-fb.c

@@ -88,11 +88,9 @@ static void mdpy_fb_destroy(struct fb_info *info)
 
 static const struct fb_ops mdpy_fb_ops = {
 	.owner		= THIS_MODULE,
+	FB_DEFAULT_IOMEM_OPS,
 	.fb_destroy	= mdpy_fb_destroy,
 	.fb_setcolreg	= mdpy_fb_setcolreg,
-	.fb_fillrect	= cfb_fillrect,
-	.fb_copyarea	= cfb_copyarea,
-	.fb_imageblit	= cfb_imageblit,
 };
 
 static int mdpy_fb_probe(struct pci_dev *pdev,