Add adapter card type identification support by reading
FPGA STAT_PRES1 register SDHC Card ID[0:2] bits. To use this function,
define CONFIG_FSL_ESDHC_ADAPTER_IDENT.

Signed-off-by: Yangbo Lu <yangbo.lu@freescale.com>
Cc: York Sun <yorksun@freescale.com>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
[York Sun: resolve conflicts in README.fsl-esdhc]
Reviewed-by: York Sun <yorksun@freescale.com>