[BUG] mx6cuboxi : broken MMC support

[François Perrad]

With 2020.07 (or 2020.04 or 2020.10), something goes wrong on this board.
I think it is related to
https://gitlab.denx.de/u-boot/u-boot/-/commit/6c3fbf3e456c49c2f43c0c286106a0d4b099b67b

2020.01 works fine with mmc0 (mmc0 is current device)
2020.07 fails with mmc1
both versions are built in the Builroot environment,
and I use a Micro SD with the Cubox.

Here, the working version 2020.01

U-Boot SPL 2020.01 (Oct 09 2020 - 22:28:05 +0200)
Trying to boot from MMC1


U-Boot 2020.01 (Oct 09 2020 - 22:28:05 +0200)

CPU:   Freescale i.MX6SOLO rev1.3 996 MHz (running at 792 MHz)
CPU:   Commercial temperature grade (0C to 95C) at 30C
Reset cause: POR
Board: MX6 Cubox-i
DRAM:  512 MiB
MMC:   FSL_SDHC: 0, FSL_SDHC: 1
Loading Environment from MMC... *** Warning - bad CRC, using default
environment

No panel detected: default to HDMI
Display: HDMI (1024x768)
In:    serial
Out:   serial
Err:   serial
Net:   FEC
Hit any key to stop autoboot:  0
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
Found U-Boot script /boot/boot.scr
336 bytes read in 106 ms (2.9 KiB/s)
## Executing script at 12000000
36612 bytes read in 121 ms (294.9 KiB/s)
8552176 bytes read in 652 ms (12.5 MiB/s)
## Flattened Device Tree blob at 18000000
   Booting using the fdt blob at 0x18000000
   Using Device Tree in place at 18000000, end 1800bf03

Starting kernel ...



Now, with the version 2020.07

U-Boot SPL 2020.07 (Oct 06 2020 - 13:33:44 +0200)
WDT:   Not found!
Trying to boot from MMC1


U-Boot 2020.07 (Oct 06 2020 - 13:33:44 +0200)

CPU:   Freescale i.MX6SOLO rev1.3 996 MHz (running at 792 MHz)
CPU:   Commercial temperature grade (0C to 95C) at 36C
Reset cause: POR
Board: MX6 Cubox-i
DRAM:  512 MiB
MMC:   FSL_SDHC: 1, FSL_SDHC: 2
Loading Environment from MMC... *** Warning - bad CRC, using default
environment

No panel detected: default to HDMI
Display: HDMI (1024x768)
In:    serial
Out:   serial
Err:   serial
Net:
Warning: ethernet at 2188000 using MAC address from ROM
eth0: ethernet at 2188000
Hit any key to stop autoboot:  0
switch to partitions #0, OK
mmc1 is current device
Scanning mmc 1:1...
Found U-Boot script /boot/boot.scr
336 bytes read in 12 ms (27.3 KiB/s)
## Executing script at 12000000
SCRIPT FAILED: continuing...
switch to partitions #0, OK
mmc2(part 0) is current device
** No partition table - mmc 2 **
No SATA device found!
starting USB...


François