[Skiboot] [PATCH 2/2] astbmc: Use oem hiomap ipmi command for bmc_sw_ami

[Lei YU]

> So I guess we have "problem" for machines like Romulus where we can
> "genuinely" be running either OpenBMC or AMI BMC firmware?

That seems to be true.

Except for the "name", the difference between bmc_plat_ast2500_ami and
bmc_plat_ast2500_openbmc is the `bmc_sw_config` struct, which defines 3 oem
IPMI commands:

  1     uint32_t ipmi_oem_partial_add_esel;
  2     uint32_t ipmi_oem_pnor_access_status;
  3     uint32_t ipmi_oem_hiomap_cmd;

* Luckily, AMI BMC uses the same oem command for ipmi_oem_partial_add_esel, so
   that's OK.
* OpenBMC has no ipmi_oem_pnor_access_status command, so Romulus PNOR loses
   this function.
* If AMI BMC uses the same oem command for hiomap, then that's OK, too.

For this patch, the problem is if AMI BMC uses the same oem command for
hiomap as OpenBMC or not.
If yes, this patch is OK.

But of course, it would be better to detect the BMC and choose the right
`bmc_sw_config` at runtime.