mtd: ubi: eba: Fix a couple of misdocumentation issues

Fixes the following W=1 kernel build warning(s):

 drivers/mtd/ubi/eba.c:1304: warning: Function parameter or member 'vidb' not described in 'ubi_eba_copy_leb'
 drivers/mtd/ubi/eba.c:1304: warning: Excess function parameter 'vid_hdr' description in 'ubi_eba_copy_leb'
 drivers/mtd/ubi/eba.c:1483: warning: Function parameter or member 'ai' not described in 'print_rsvd_warning'

Cc: Richard Weinberger <richard@nod.at>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: linux-mtd@lists.infradead.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20201109182206.3037326-12-lee.jones@linaro.org

drivers/mtd/ubi/eba.c

@@ -1290,7 +1290,7 @@ static int is_error_sane(int err)
  * @ubi: UBI device description object
  * @from: physical eraseblock number from where to copy
  * @to: physical eraseblock number where to copy
- * @vid_hdr: VID header of the @from physical eraseblock
+ * @vidb: data structure from where the VID header is derived
  *
  * This function copies logical eraseblock from physical eraseblock @from to
  * physical eraseblock @to. The @vid_hdr buffer may be changed by this
@@ -1463,6 +1463,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 /**
  * print_rsvd_warning - warn about not having enough reserved PEBs.
  * @ubi: UBI device description object
+ * @ai: UBI attach info object
  *
  * This is a helper function for 'ubi_eba_init()' which is called when UBI
  * cannot reserve enough PEBs for bad block handling. This function makes a