mmc: sdhci: Introduce sdhci_calc_clk()

In order to remove the SDHCI_QUIRK2_NEED_DELAY_AFTER_INT_CLK_RST and to
reduce code duplication, put the code relative to the SD clock
configuration in a function which can be used by hosts for the
implementation of the ->set_clock() callback.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 0f39f4f..9db5090 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -661,6 +661,8 @@
 	return !!(host->flags & SDHCI_SDIO_IRQ_ENABLED);
 }
 
+u16 sdhci_calc_clk(struct sdhci_host *host, unsigned int clock,
+		   unsigned int *actual_clock);
 void sdhci_set_clock(struct sdhci_host *host, unsigned int clock);
 void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
 		     unsigned short vdd);