cpufreq: stats: Print error messages if table initialization fails

Failing to initialize cpufreq_stats table effectively disables
cpufreq_stats. Such failures should not be silent. Print error
messages when cpufreq_stats fails to create stats table.

Change-Id: I71cc0dd8262c7c6946e169f148ae39bd8f213a96
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>