RomFS MTD and NAND Flash with ECC (EUCLEAN).

[Bill Pringlemeir]

The macro ROMFS_MTD_READ seems to be passing on 'EUCLEAN' to the main
RomFs code which doesn't deal with this error code.  I think that the
'EUCLEAN' means that my 'mxc_nand' flash driver has performed error
correction.  I also see that most of the mtd tests change this error
code to mean zero.  So I think the RomFs MTD code needs something like
attached.  A large file allows md5sum, cp, etc with this patch.
Without, strace shows 'cp' getting an 'EIO' error and giving up.

Signed-off-by: Bill Pringlemeir <bpringle at sympatico.ca>