OMAP1 clock: fix for "BUG: spinlock lockup on CPU#0"

Commit 52650505 caused clock initialization
to fail on OMAP1 with "BUG: spinlock lockup on CPU#0" -- this is because
omap1_select_table_rate() and omap1_round_to_table_rate() call clk_get_rate()
with the clockfw spinlock held.  Fix by accessing the rate directly from
the internal clock framework functions.

Thanks to Tony Lindgren <tony@atomide.com> for reporting and testing the fix.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tony Lindgren <tony@atomide.com>