omap16xx: Removes fixme no longer needed in ocpi_enable()

This removes the FIXME message above ocpi_enable being declared
for proper locking in this function. As of the current kernel
verisons there is no need for locking as only one driver uses
this function currently and therefore there is no need for real
locking requirements.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>