OMAP3 clock: McBSP 2, 3, 4 functional clock parent is PER_96M_FCLK, not CORE_96M_FCLK

The correct parent of the McBSP 2, 3, and 4 functional clocks is
PER_96M_FCLK, not CORE_96M_FCLK.  Fix this in the OMAP clock tree.
Reported by Nicole Chalhoub <n-chalhoub@ti.com>.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Nicole Chalhoub <n-chalhoub@ti.com>