OMAP: McBSP: Do not enable or disable clocks on failed path

McBSP clocks are being double enabled in the event the
McBSP is already active. Also, they are unnecessarily
disabled when there's no active McBSP in use. Fix this
phenomenom by enabling and disabling the clocks at the
proper location.

Signed-off-by: Eero Nurkkala <ext-eero.nurkkala@nokia.com>
Acked-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>