[U-Boot] [PATCH V2] ARM: imx: fsl_esdhc: fix usage of low 4 bits of sysctl register

[Hector Palacios <hector.palacios@digi.com>]

On 12/04/2015 08:32 PM, Eric Nelson wrote:
> The low four bits of the SYSCTL register are reserved on the USDHC
> controller on i.MX6 and i.MX7 processors, but are used for clocking
> operations on earlier models.
> 
> Guard against their usage by hiding the bit mask macros on those
> processors.
> 
> These bits are used to prevent glitches when changing clocks on
> i.MX35 et al. Use the RSTA bit instead for i.MX6 and i.MX7.
> 
> From the i.MX6DQ RM:
> 	To prevent possible glitch on the card clock, clear the
> 	FRC_SDCLK_ON bit when changing clock divisor value(SDCLKFS
> 	or DVS in System Control Register) or setting RSTA bit.
> 
> Signed-off-by: Eric Nelson <eric@nelint.com>

Reviewed-by: Hector Palacios <hector.palacios@digi.com>