mmc: sdhci-of-esdhc: modify the sd clock in of_match_node way

Convert to use of_match_node method to fix up eSDHC clock for
ls1046a/ls1012a/p1010. Also add eSDHC clock fixup for ls1021a
according to its datasheet. The maxmum speed for ls1021a eSDHC
high speed mode is 46.5MHz.

Signed-off-by: Yinbo Zhu <yinbo.zhu@nxp.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>