ACPI: processor: Check for null return of devm_kzalloc() in fch_misc_setup()

devm_kzalloc() may fail, clk_data->name might be NULL and will
cause a NULL pointer dereference later.

Signed-off-by: Kang Chen <void0red@gmail.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>