x86/mce: Recognise machine check bank signature for data path error

Action required data path signature is defined in table 15-19 of SDM:

+-----------------------------------------------------------------------------+
| SRAR Error | Valid | OVER | UC | EN | MISCV | ADDRV | PCC | S | AR | MCACOD |
| Data Load  |     1 |    0 |  1 |  1 |     1 |     1 |   0 | 1 |  1 |  0x134 |
+-----------------------------------------------------------------------------+

Recognise this, and pass MCE_AR_SEVERITY code back to do_machine_check() if
we have the action handler configured (CONFIG_MEMORY_FAILURE=y)

Acked-by: Borislav Petkov <bp@amd64.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>