fbdev/tridentfb: Initialize fb_ops to fbdev I/O-memory helpers

Initialize the instance of struct fb_ops with fbdev initializer
macros for framebuffers in I/O address space. Set the read/write,
draw and mmap callbacks to the correct implementation and avoid
implicit defaults. Also select the necessary I/O helpers in Kconfig.

Fbdev drivers sometimes rely on the callbacks being NULL for a
default implementation to be invoked; hence requiring the I/O
helpers to be built in any case. Setting all callbacks in all
drivers explicitly will allow to make the I/O helpers optional.
This benefits systems that do not use these functions.

No functional changes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230927074722.6197-43-tzimmermann@suse.de

drivers/video/fbdev/Kconfig

@@ -1375,6 +1375,7 @@ config FB_TRIDENT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
 	select FB_DDC
+	select FB_IOMEM_FOPS
 	select FB_MODE_HELPERS
 	select VIDEO_NOMODESET
 	help

drivers/video/fbdev/tridentfb.c

@@ -1444,6 +1444,7 @@ static int tridentfb_blank(int blank_mode, struct fb_info *info)
 
 static const struct fb_ops tridentfb_ops = {
 	.owner = THIS_MODULE,
+	__FB_DEFAULT_IOMEM_OPS_RDWR,
 	.fb_setcolreg = tridentfb_setcolreg,
 	.fb_pan_display = tridentfb_pan_display,
 	.fb_blank = tridentfb_blank,
@@ -1453,6 +1454,7 @@ static const struct fb_ops tridentfb_ops = {
 	.fb_copyarea = tridentfb_copyarea,
 	.fb_imageblit = tridentfb_imageblit,
 	.fb_sync = tridentfb_sync,
+	__FB_DEFAULT_IOMEM_OPS_MMAP,
 };
 
 static int trident_pci_probe(struct pci_dev *dev,