ACPI: CPPC: fix some coding style issues

Fix some coding style issues reported by checkpatch.pl, including the
following types:

WARNING: Missing a blank line after declarations
WARNING: unnecessary whitespace before a quoted newline
ERROR: spaces required around that '>='
ERROR: switch and case should be at the same indent

Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>