power: remove redundant close of frequency file

power: remove redundant close of frequency file

Previous fix has addressed the incorrect handling of `base_frequency`
file, but has added a use-after-free error due to the fact that all
further code paths will lead to an `fclose()` call at the end, so the
additional `fclose()` call right after processing the file was
unnecessary.

Coverity issue: 369901
Fixes: 8a5febaac4f7 ("power: fix P-state base frequency handling")

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Reviewed-by: Liang Ma <liangma@liangbit.com>
Acked-by: David Hunt <david.hunt@intel.com>