arm64: Remove exporting cpu_logical_map symbol

Commit eaecca9e ("arm64: Fix __cpu_logical_map undefined issue")
exported cpu_logical_map in order to fix tegra194-cpufreq module build
failure.

As this might potentially cause problem while supporting physical CPU
hotplug, tegra194-cpufreq module was reworded to avoid use of
cpu_logical_map() via the commit 93d0c1ab

 ("cpufreq: replace
cpu_logical_map() with read_cpuid_mpir()")

Since cpu_logical_map was exported to fix the module build temporarily,
let us remove the same before it gains any user again.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20200901095229.56793-1-sudeep.holla@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>