Revert "OPP: Add dev_pm_opp_find_freq_exact_indexed()"

This reverts commit 7baa59f8 which is
commit a5893928 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I00b677f975738c791bf7074c982a8e215f8054ac
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>