When the power_intel_uncore_autotest unit test is run as an unprivileged
user which cannot init the power library, it crashes the unit test
binary due to calling "rte_power_uncore_exit" after the first test case
(initialization) fails. This crash is due to trying to write to NULL
file handles.

Fix the crash by checking each file handle is non-null before writing to
it and closing it.

Fixes: 60b8a661a957 ("power: add Intel uncore frequency control")
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 drivers/power/intel_uncore/intel_uncore.c | 35 ++++++++++++-----------
 1 file changed, 18 insertions(+), 17 deletions(-)

Acked-by: Kevin Laatz <kevin.laatz@intel.com>