QSPI bug with Portenta C33

[umbynos]

While experimenting with Portenta C33 and certificate upload I discovered a bug 🐛 :
When a file is uploaded in the external QSPI of the board somehow it's corrupted.
To reproduce:

1. flash the board with the UsbMsd/examples/MSD_QSPI/ example
2. upload a file to the board using the new example in Add new example (we'll need it in the fwuploader) #2 or simply by copying to the mounted FS ( cp SSH_1.pdf /media/umberto/EB9F-C47C/SSH_1.pdf) ( the file I uploaded is here: SSH_1.pdf
3. reset the board
4. download the file from the mounted drive ( cp /media/umberto/EB9F-C47C/SSH_1.pdf SSH_1_new.pdf) (the file I got is here:
   SSH_1_new.pdf
5. the files are different:

$ md5sum SSH_1.pdf
fba0dc994d857d5eee569ce2057b1b54  SSH_1.pdf
$ md5sum SSH_1_new.pdf 
b273108e7e4616afa33a5094d4c00068  SSH_1_new.pdf

7. vbindiff SSH_1.pdf SSH_1_new.pdf:
   

I don't know if that USBS in the vbindiff output could be a hint...

[facchinm]

To be retested on top of #85

[pennam]

Works without issues with latest core release (1.0.4)