EDAC/sb_edac: Fix the compile warning of large frame size

Compiling sb_edac driver with GCC 11.4.0 and the W=1 option reported
the following warning:

  drivers/edac/sb_edac.c: In function ‘sbridge_mce_output_error’:
  drivers/edac/sb_edac.c:3249:1: warning: the frame size of 1032 bytes is larger than 1024 bytes [-Wframe-larger-than=]

As there is no concurrent invocation of sbridge_mce_output_error(),
fix this warning by moving the large-size variables 'msg' and 'msg_full'
from the stack to the pre-allocated data segment.

[Tony: Fix checkpatch warnings for code alignment & use of strcpy()]

Reported-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Zhang Rui <rui.zhang@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/20240829120903.84152-1-qiuxu.zhuo@intel.com