ARM: am33xx: clk: Update clkdev table to add mcasp alias

After Rajendra's common-clock preparation series,
commit (a1978ef4da1 - ARM: omap: hwmod: get rid of
all omap_clk_get_by_name usage) the clkdev table need to
update with an entry for clocks used by hwmod to have
clock name same as the alias.

Without this, the clk_get() in omap_hwmod would fail.

Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>