Removes some functions that are not used anywhere:
omap_pm_set_max_dev_wakeup_lat() omap_pm_if_exit() omap_pm_cpu_get_freq()
omap_pm_cpu_set_freq() omap_pm_cpu_get_freq_table() omap_pm_dsp_get_opp()
omap_pm_dsp_set_min_opp() omap_pm_dsp_get_opp_table()
omap_pm_set_min_clk_rate() omap_pm_set_max_sdma_lat()

This was partially found by using a static code analysis program called cppcheck.
Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Tony Lindgren <tony@atomide.com>