[ARM] omap: eliminate unnecessary conditionals in omap2_clk_wait_ready

Rather than employing run-time tests in omap2_clk_wait_ready() to
decide whether we need to wait for the clock to become ready, we
can set the .ops appropriately.

This change deals with the OMAP24xx and OMAP34xx conditionals only.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>