Add a get_max_clock() handler to sdhci-of-aspeed to report f_max as the
maximum clock rate if it is set. This enables artificial limitation of
the bus speed via max-frequency in the devicetree for e.g. the AST2600
evaluation board where I was seeing errors at 200MHz.
Signed-off-by: NAndrew Jeffery <andrew@aj.id.au>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>