Support reading HW UIDs (serial numbers) from OTPs

Depends on: !42 (merged)
Issue: https://git.kontron-electronics.de/sw/ked/plan/plan-ked-bootloader/-/issues/7

CC: @estoll

Tested on:

• BL i.MX8MM
• BL i.MX8MP
• BL i.MX6ULL

Example Log i.MX8MP with Board ID in GP2 Fuse-Register:

    U-Boot 2024.01_ked-kirkstone_0.0.0-dev+ga15acbb0b04+p5141 (Jan 18 2024 - 16:29:46 +0100)

    CPU:   Freescale i.MX8MP[8] rev1.1 1600 MHz (running at 1200 MHz)
    CPU:   Industrial temperature grade (-40C to 105C) at 50C
    [...]
    SEC0:  RNG instantiated
+   Serial Number: 0042152331 (BOARD)
    Net: [...]

Example Log i.MX8MP with SoM ID in GP1 Fuse-Register and empty GP2:

    U-Boot 2024.01_ked-kirkstone_0.0.0-dev+ga15acbb0b04+p5141 (Jan 18 2024 - 16:29:46 +0100)

    CPU:   Freescale i.MX8MP[8] rev1.1 1600 MHz (running at 1200 MHz)
    CPU:   Industrial temperature grade (-40C to 105C) at 49C
    [...]
    SEC0:  RNG instantiated
+   Serial Number: 0030124840 (SOM)
    Net: [...]

Example Log i.MX8MP with empty GP1 and GP2 and CONFIG_KONTRON_HW_UID_USE_SOC_FALLBACK=y:

    U-Boot 2024.01_ked-kirkstone_0.0.0-dev+ga15acbb0b04+p5141 (Jan 18 2024 - 16:29:46 +0100)

    CPU:   Freescale i.MX8MP[8] rev1.1 1600 MHz (running at 1200 MHz)
    CPU:   Industrial temperature grade (-40C to 105C) at 52C
    [...]
    SEC0:  RNG instantiated
+   Serial Number: 4696668CD9516886 (SOC)
    Net: [...]

Example Log i.MX8MP with empty GP1 and GP2 and CONFIG_KONTRON_HW_UID_USE_SOC_FALLBACK=n:

    U-Boot 2024.01_ked-kirkstone_0.0.0-dev+ga15acbb0b04+p5141 (Jan 18 2024 - 16:29:46 +0100)

    CPU:   Freescale i.MX8MP[8] rev1.1 1600 MHz (running at 1200 MHz)
    CPU:   Industrial temperature grade (-40C to 105C) at 52C
    [...]
    SEC0:  RNG instantiated
+   Serial Number: None
    Net: [...]