EDAC/amd64: Use DEVICE_ATTR helper macros

Instead of "open coding" DEVICE_ATTR, use the corresponding
helper macros DEVICE_ATTR_{RW,RO,WO} in amd64_edac.c

Some function names needed to be changed to match the device
conventions <foo>_show and <foo>_store, but the functionality
itself is unchanged.

The devices using EDAC_DCT_ATTR_SHOW() are left unchanged.

Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Dwaipayan Ray <dwaipayanray1@gmail.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20210713065130.2151-1-dwaipayanray1@gmail.com