fs/fs.h: Add register_driver_with_size function

It acts as register_driver but also populates the inode size.
This allows to return a non-zero size when calling stat() on an eeprom
driver.

The conditions (CONFIG_PSEUDOFS_FILE or CONFIG_FS_SHMFS) for the
declaration of the inode size field have also been removed so that other
drivers can populate this field in the future.

Signed-off-by: Antoine Juckler <6445757+ajuckler@users.noreply.github.com>

include/nuttx/fs/fs.h

@@ -407,9 +407,7 @@ struct inode
   uint16_t          i_flags;    /* Flags for inode */
   union inode_ops_u u;          /* Inode operations */
   ino_t             i_ino;      /* Inode serial number */
-#if defined(CONFIG_PSEUDOFS_FILE) || defined(CONFIG_FS_SHMFS)
   size_t            i_size;     /* The size of per inode driver */
-#endif
 #ifdef CONFIG_PSEUDOFS_ATTRIBUTES
   mode_t            i_mode;     /* Access mode flags */
   uid_t             i_owner;    /* Owner */
@@ -625,6 +623,35 @@ int register_driver(FAR const char *path,
                     FAR const struct file_operations *fops, mode_t mode,
                     FAR void *priv);
 
+/****************************************************************************
+ * Name: register_driver_with_size
+ *
+ * Description:
+ *   Register a character driver inode into the pseudo file system and
+ *   assign a size to it.
+ *
+ * Input Parameters:
+ *   path - The path to the inode to create
+ *   fops - The file operations structure
+ *   mode - inmode privileges
+ *   priv - Private, user data that will be associated with the inode.
+ *   size - Size in bytes to assign to the driver
+ *
+ * Returned Value:
+ *   Zero on success (with the inode point in 'inode'); A negated errno
+ *   value is returned on a failure (all error values returned by
+ *   inode_reserve):
+ *
+ *   EINVAL - 'path' is invalid for this operation
+ *   EEXIST - An inode already exists at 'path'
+ *   ENOMEM - Failed to allocate in-memory resources for the operation
+ *
+ ****************************************************************************/
+
+int register_driver_with_size(FAR const char *path,
+                              FAR const struct file_operations *fops,
+                              mode_t mode, FAR void *priv, size_t size);
+
 /****************************************************************************
  * Name: register_blockdriver
  *