doc: imx: psb: Add documentation for MX8MM behavior with Fast Boot fuse blown

On iMX8MM with Fast Boot fuse blown, the SIT and A-copy image are
placed at different offset than on iMX8MM with Fast Boot fuse NOT
blown. List both options and both offsets to avoid confusion.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Ye Li <ye.li@nxp.com>
Cc: uboot-imx <uboot-imx@nxp.com>
Reviewed-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
diff --git a/doc/board/nxp/psb.rst b/doc/board/nxp/psb.rst
index 3533c91..2eccdcf 100644
--- a/doc/board/nxp/psb.rst
+++ b/doc/board/nxp/psb.rst
@@ -75,13 +75,15 @@
 For details on the addition of two numbers in recommended B-copy offset, see
 SIT format below.
 
-+----------+--------------------+-----------------------+-----------------------------+
-|   SoC    | SIT offset (fixed) | A-copy offset (fixed) | B-copy offset (recommended) |
-+----------+--------------------+-----------------------+-----------------------------+
-| iMX7D    |         0x1        |          0x2          |          0x800+0x2          |
-+----------+--------------------+-----------------------+-----------------------------+
-| iMX8MM   |        0x41        |         0x42          |         0x1000+0x42         |
-+----------+--------------------+-----------------------+-----------------------------+
++----------+-----------------------------+--------------------+-----------------------+-----------------------------+
+|   SoC    | Boot Device Type            | SIT offset (fixed) | A-copy offset (fixed) | B-copy offset (recommended) |
++----------+-----------------------------+--------------------+-----------------------+-----------------------------+
+| iMX7D    |                             |         0x1        |          0x2          |          0x800+0x2          |
++----------+-----------------------------+--------------------+-----------------------+-----------------------------+
+| iMX8MM   | SD/eSD/MMC/eMMC normal boot |        0x41        |         0x42          |         0x1000+0x42         |
++----------+-----------------------------+--------------------+-----------------------+-----------------------------+
+| iMX8MM   | eMMC Fast boot fuse blown   |         0x1        |          0x2          |          0x1000+0x2         |
++----------+-----------------------------+--------------------+-----------------------+-----------------------------+
 
 SIT format
 ~~~~~~~~~~