mx25: Select the ESDHC_A001 erratum

When a high speed card is connected to mx25 the following error is seen:

U-Boot 2017.11-rc2-00104-gb79372a (Oct 31 2017 - 11:02:22 -0200)

CPU:   Freescale i.MX25 rev1.2 at 399 MHz
Reset cause: POR
Board: MX25PDK
I2C:   ready
DRAM:  64 MiB
No arch specific invalidate_icache_all available!
MMC:   FSL_SDHC: 0
*** 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

, which prevents any usage of the SD card.

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.MX25 errata document,
I have confirmed with the NXP design team that this erratum does affect
i.MX25, so fix the problem by selecting SYS_FSL_ERRATUM_ESDHC_A001
at SoC level.

Successfully tested with a high speed SD card on a mx25pdk board.

Suggested-by: Benoît Thébaudeau <benoit@wsystem.com>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
Acked-by: Otavio Salvador <otavio@ossystems.com.br>
Tested-by: Otavio Salvador <otavio@ossystems.com.br> # mx25pdk

arch/arm/mach-imx/mx2/Kconfig

@@ -3,6 +3,7 @@ if ARCH_MX25
 config MX25
 	bool
 	default y
+	select SYS_FSL_ERRATUM_ESDHC_A001
 choice
 	prompt "MX25 board select"
 	optional