soc: qcom: socinfo: remove APIs without any clients

socinfo exports a number of APIs left over from the days before
device tree, for targets which are no longer supported in the
current kernel. Remove these unused APIs:
 get_core_count()
 read_msm_cpu_type()
 cpu_is_*()
 soc_class_is_*()

Change-Id: I2fb23c44649f0582fb0e2523a0235470f76a3da9
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>