drm/amd/display: Fix comparison error in dcn21 DML

stable inclusion
from stable-5.10.57
commit f9d875c8c92f1bdaeeb3eeccbf8402974f20cd31
bugzilla: 176179 https://gitee.com/openeuler/kernel/issues/I4DZ64

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f9d875c8c92f1bdaeeb3eeccbf8402974f20cd31



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

[ Upstream commit ec3102dc ]

[why]
A comparison error made it possible to not iterate through all the
specified prefetch modes.

[how]
Correct "<" to "<="

Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: Yongqiang Sun <Yongqiang.Sun@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Victor Lu <victorchengchi.lu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>