cpufreq: armada-37xx: Remove cur_frequency variable

Variable cur_frequency in armada37xx_cpufreq_driver_init() is unused.

Signed-off-by: Pali Rohár <pali@kernel.org>
Acked-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Tested-by: Tomasz Maciej Nowak <tmn505@gmail.com>
Tested-by: Anders Trier Olesen <anders.trier.olesen@gmail.com>
Tested-by: Philip Soares <philips@netisense.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>