cpufreq: powernv: Dont assume distinct pstate values for nominal and pmin

cpufreq: powernv: Dont assume distinct pstate values for nominal and pmin

BugLink: http://bugs.launchpad.net/bugs/1746174
Some OpenPOWER boxes can have same pstate values for nominal and
pmin pstates. In these boxes the current code will not initialize
'powernv_pstate_info.min' variable and result in erroneous CPU
frequency reporting. This patch fixes this problem.

Fixes: 09ca4c9b5958 (cpufreq: powernv: Replacing pstate_id with frequency table index)
Reported-by: Alvin Wang <wangat@tw.ibm.com>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.8+ <stable@vger.kernel.org> # 4.8+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 3fa4680b860bf48b437d6a2c039789c4abe202ae)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
Acked-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>