sdhci-of: fix SD clock calculation

Linear divisor's values in a register start at 0 (zero means "divide by
1").  Before this patch the code didn't account that fact, so SD cards
were running underclocked.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Pierre Ossman <pierre@ossman.eu>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: David Vrabel <david.vrabel@csr.com>
Cc: Ben Dooks <ben@fluff.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/mmc/host/sdhci-of.c

@@ -136,6 +136,7 @@ static void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
 	}
 
 	pre_div >>= 1;
+	div--;
 
 	setbits32(host->ioaddr + ESDHC_SYSTEM_CONTROL, ESDHC_CLOCK_IPGEN |
 		  ESDHC_CLOCK_HCKEN | ESDHC_CLOCK_PEREN |