fbdev: Harmonize some comments in <linux/fb.h>

Make the comments for I/O, system and DMA memory say the same.
Makes the header file's structure more obvious.
Suggested-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230707083422.18691-13-tzimmermann@suse.de

include/linux/fb.h

@@ -526,7 +526,7 @@ extern int fb_pan_display(struct fb_info *info, struct fb_var_screeninfo *var);
 extern int fb_blank(struct fb_info *info, int blank);
 
 /*
- * Drawing operations where framebuffer is in I/O memory
+ * Helpers for framebuffers in I/O memory
  */
 
 extern void cfb_fillrect(struct fb_info *info, const struct fb_fillrect *rect);
@@ -537,10 +537,6 @@ extern ssize_t fb_io_read(struct fb_info *info, char __user *buf,
 extern ssize_t fb_io_write(struct fb_info *info, const char __user *buf,
 			   size_t count, loff_t *ppos);
 
-/*
- * Initializes struct fb_ops for framebuffers in I/O memory.
- */
-
 #define __FB_DEFAULT_IO_OPS_RDWR \
 	.fb_read	= fb_io_read, \
 	.fb_write	= fb_io_write
@@ -559,7 +555,7 @@ extern ssize_t fb_io_write(struct fb_info *info, const char __user *buf,
 	__FB_DEFAULT_IO_OPS_MMAP
 
 /*
- * Drawing operations where framebuffer is in system RAM
+ * Helpers for framebuffers in system memory
  */
 
 extern void sys_fillrect(struct fb_info *info, const struct fb_fillrect *rect);
@@ -570,10 +566,6 @@ extern ssize_t fb_sys_read(struct fb_info *info, char __user *buf,
 extern ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
 			    size_t count, loff_t *ppos);
 
-/*
- * Initializes struct fb_ops for framebuffers in system memory.
- */
-
 #define __FB_DEFAULT_SYS_OPS_RDWR \
 	.fb_read	= fb_sys_read, \
 	.fb_write	= fb_sys_write