When a high speed card is connected to mx51evk the following error is seen:

U-Boot 2017.11-rc2 (Oct 18 2017 - 13:49:26 -0200)

CPU:   Freescale i.MX51 rev3.0 at 800 MHz
Reset cause: POR
Board: MX51EVK
DRAM:  512 MiB
MMC:   FSL_SDHC: 0, FSL_SDHC: 1
*** Warning - read failed, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   FEC
Hit any key to stop autoboot:  0
=> saveenv
Saving Environment to MMC...
Writing to MMC(0)... failed

The root cause for the failure is the eSDHC-A001 erratum:

"eSDHC-A001 : Data timeout counter (SYSCTL[DTOCV]) is not reliable for
values of 0x4,0x8, and 0xC" that is listed
on some PowerArchitecture chips:
https://www.nxp.com/files-static/32bit/doc/errata/MPC8379ECE.pdf



Even though eSDHC-A001 is not documented on the i.MX51 errata document,
I have confirmed with the NXP design team that this erratum does affect
i.MX51, so fix the problem by selecting SYS_FSL_ERRATUM_ESDHC_A001
at SoC level.

The i.MX51 ts4800 board already selects this option, but it is better
to move this selection to the i.MX51 SoC level instead.

Successfully tested with a high speed SD card on a mx51evk board.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>