fbdev/sm501fb: Initialize fb_ops to fbdev I/O-memory helpers

Initialize each 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/20230927074722.6197-37-tzimmermann@suse.de

drivers/video/fbdev/Kconfig

@@ -1667,6 +1667,7 @@ config FB_SM501
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
+	select FB_IOMEM_FOPS
 	help
 	  Frame buffer driver for the CRT and LCD controllers in the Silicon
 	  Motion SM501.

drivers/video/fbdev/sm501fb.c

@@ -1452,6 +1452,7 @@ static void sm501fb_fillrect(struct fb_info *info, const struct fb_fillrect *rec
 
 static struct fb_ops sm501fb_ops_crt = {
 	.owner		= THIS_MODULE,
+	__FB_DEFAULT_IOMEM_OPS_RDWR,
 	.fb_check_var	= sm501fb_check_var_crt,
 	.fb_set_par	= sm501fb_set_par_crt,
 	.fb_blank	= sm501fb_blank_crt,
@@ -1462,10 +1463,12 @@ static struct fb_ops sm501fb_ops_crt = {
 	.fb_copyarea	= sm501fb_copyarea,
 	.fb_imageblit	= cfb_imageblit,
 	.fb_sync	= sm501fb_sync,
+	__FB_DEFAULT_IOMEM_OPS_MMAP,
 };
 
 static struct fb_ops sm501fb_ops_pnl = {
 	.owner		= THIS_MODULE,
+	__FB_DEFAULT_IOMEM_OPS_RDWR,
 	.fb_check_var	= sm501fb_check_var_pnl,
 	.fb_set_par	= sm501fb_set_par_pnl,
 	.fb_pan_display	= sm501fb_pan_pnl,
@@ -1476,6 +1479,7 @@ static struct fb_ops sm501fb_ops_pnl = {
 	.fb_copyarea	= sm501fb_copyarea,
 	.fb_imageblit	= cfb_imageblit,
 	.fb_sync	= sm501fb_sync,
+	__FB_DEFAULT_IOMEM_OPS_MMAP,
 };
 
 /* sm501_init_cursor