EDAC/skx_common: Use driver decoder first

The performance of driver decoder[1] is better than the performance
of firmware decoder[2], especially on frequent correctable errors.

So use the driver decoder first, fall back to firmware decoder if
the driver decoder is unavailable. Also rename the function pointer
skx_decode to driver_decode (better name to contrast with adxl_decode).

[1] Decode errors by extracting error information from registers of
    memory controllers and/or MCA bank registers.

[2] Decode errors by calling ACPI DSM methods.

Co-developed-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/all/20220901194310.115427-1-tony.luck@intel.com/