platform/x86/amd/pmc: adjust getting DRAM size behavior

platform/x86/amd/pmc: adjust getting DRAM size behavior

amd_pmc_get_dram_size() is used to get the DRAM size information. But
in the current code, mailbox command to get the DRAM size info is sent
based on the values of dev->major and dev->minor.

But dev->major and dev->minor will have either junk or zero assigned to
them until at least once a call to amd_pmc_get_smu_version() is made
which ideally populates dev->major and dev->minor.

However, adding a amd_pmc_get_smu_version() call to
amd_pmc_get_dram_size() has a downside of elevating the boot times.

After talking to the PMFW team, it's understood that the "get dram
size" mbox command would only be supported on specific platforms (like
Mendocino) and not all. So, adjust getting DRAM size behavior such
that,

- if running on Rembrandt or Mendocino and the underlying PMFW knows
how to execute the "get dram size" command it shall give the custom
dram size.

- if the underlying FW does not report the dram size, we just proceed
further and assign the default dram size.

The simplest way to address this is to remove amd_pmc_get_dram_size()
function and directly call the "get dram size" command in the
amd_pmc_s2d_init().

Reported-by: Mark Hasemeyer <markhas@chromium.org>
Fixes: be8325fb3d8c ("platform/x86/amd: pmc: Get STB DRAM size from PMFW")
Cc: stable@vger.kernel.org
Suggested-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20231116170121.3372222-1-Shyam-sundar.S-k@amd.com
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>