ACPI: Revert "ACPI: Remove CONFIG_ACPI_PROCFS_POWER and cm_sbsc.c"

The commit 1e2d9cdf and 7d7ee958 remove ACPI Proc Battery
directory and breaks some old userspace tools. This patch
is to revert 7d7ee958.

Fixes: 7d7ee958 (ACPI: Remove CONFIG_ACPI_PROCFS_POWER and cm_sbsc.c)
Cc: 3.13+ <stable@vger.kernel.org> # 3.13+
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>