MMC: OMAP: Remove extra divisor increase

As noted by Kyungmin Park, the divisor calculation has
an unnecessary increase.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Carlos Eduardo Aguiar <carlos.aguiar@indt.org.br>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>