ACPICA: Cleanup for all string-to-integer conversions

ACPICA commit e2e72a351201fd58e4694418859ae2c247dafca0

Consolidate multiple versions of strtoul64 to one common version.
limit possible bases to either 10 or 16.
Handles both implicit and explicit conversions.
Added a 2-character ascii-to-hex function for GPEs and buffers.
Adds a new file, utstrtoul64.c

Link: https://github.com/acpica/acpica/commit/e2e72a35


Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>