EDAC/bluefield: Use Arm SMC for EMI access on BlueField-2

EDAC/bluefield: Use Arm SMC for EMI access on BlueField-2

The BlueField EDAC driver supports the first generation BlueField-1 SoC, but
not the second generation BlueField-2 SoC. The BlueField-2 SoC is different in
that only secure accesses are allowed to the External Memory Interface (EMI)
register block. On BlueField-2, all read/write accesses from Linux to EMI
registers are routed via the Arm Secure Monitor Call (SMC) through Arm Trusted
Firmware (ATF), which runs at EL3 privileged state.

On BlueField-1, EMI registers are mapped and accessed directly. In order to
support BlueField-2, the driver's read and write access methods must be
extended with additional logic to include secure access to the EMI registers
via SMCs.

  [ bp: Move struct member comments above them, simplify. ]

Signed-off-by: David Thompson <davthompson@nvidia.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shravan Kumar Ramani <shravankr@nvidia.com>
Link: https://lore.kernel.org/r/20241021233013.18405-1-davthompson@nvidia.com