board: stm32mp1: add finished good in board identifier OTP

board: stm32mp1: add finished good in board identifier OTP

Update the command stboard to support the updated coding of OTP 59 with
finished good.

The ST product codification have several element
- "Commercial Product Name" (CPN): type of product board (DKX, EVX)
  associated to the board ID "MBxxxx"
- "Finished Good" or "Finish Good" (FG):
  effective content of the product without chip STM32MP1 (LCD, Wifi, …)
- BOM: cost variant for same FG
  (for example, several provider of the same component)

For example
- commercial product = STM32MP157C-EV1
- Finished Good = EVA32MP157A1$AU1

Booth information are written on board and these information is also saved
in OTP59:

bit [31:16] (hex) => Board id, MBxxxx
bit [15:12] (dec) => Variant CPN (1....15)
bit [11:8]  (dec) => Revision board (index with A = 1, Z = 26)
bit [7:4]   (dec) => Variant FG : finished good (NEW)
bit [3:0]   (dec) => BOM (01, .... 255)

The updated command is:
  stboard [-y] <Board> <VarCPN> <Revision> <VarFG> <BOM>

And the displayed STMicroelectronics board identification is:
  Board: MB<Board> Var<VarCPN>.<VarFG> Rev.<Revision>-<BOM>

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>