drm/amd/display: Exit idle optimizations before attempt to access PHY

stable inclusion
from stable-v5.10.205
commit 357badc01add6e98dd69c9831843da9cc3e905e9
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8AS5P
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v5.10.205&id=357badc01add6e98dd69c9831843da9cc3e905e9



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[ Upstream commit de612738 ]

[Why & How]
DMUB may hang when powering down pixel clocks due to no dprefclk.

It is fixed by exiting idle optimization before the attempt to access PHY.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Leo Chen <sancchen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Baogen Shang <baogen.shang@windriver.com>