drm/amdgpu: fix xclk freq on CHIP_STONEY

stable inclusion
from stable-v5.10.184
commit 00380551353be6581815efb2f1ff9c687a2f40df
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8IRR2

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=00380551353be6581815efb2f1ff9c687a2f40df



--------------------------------

commit b447b079 upstream.

According to Alex, most APUs from that time seem to have the same issue
(vbios says 48Mhz, actual is 100Mhz).  I only have a CHIP_STONEY so I
limit the fixup to CHIP_STONEY

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>