cpufreq / OPP: allow allocation of extra table entries in freq_table

cpufreq / OPP: allow allocation of extra table entries in freq_table

Prefix dev_pm_opp_init_cpufreq_table() with "__" and add a wrapper
for it to keep current users unchanged.  Then add an extra_opps
parameter to __dev_pm_opp_init_cpufreq_table() to allow allocation of
extra table entries in freq_table.

This patch is a preparation for adding 'boost' mode frequencies
support to cpufreq-dt driver.

Cc: Tomasz Figa <tomasz.figa@gmail.com>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>