Updated sos firmware causes problems with kernel 4.19.  Need to
figure out what breaks with that kernel and backport the fix,
until then, revert it.

bug: https://bugs.freedesktop.org/show_bug.cgi?id=110733
bug: https://bugzilla.kernel.org/show_bug.cgi?id=203627

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>