cpufreq: vexpress-spc: drop unnessary cpufreq_arm_bL_ops abstraction

cpufreq_arm_bL_ops is no longer needed after merging the generic
arm_big_little and vexpress-spc driver. Remove it along with the
unused bL_cpufreq_{,un}register routines and rename some bL_*
functions to ve_spc_*.

Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>