drm/i915: Use correct downstream caps for check Src-Ctl mode for PCON

drm/i915: Use correct downstream caps for check Src-Ctl mode for PCON

Fix the typo in DPCD caps used for checking SRC CTL mode of
HDMI2.1 PCON

v2: Corrected Fixes tag (Jani Nikula).
v3: Rebased.

Fixes: 04b6603d13be ("drm/i915/display: Configure HDMI2.1 Pcon for FRL only if Src-Ctl mode is available")
Cc: Ankit Nautiyal <[email protected]>
Cc: Uma Shankar <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: "Ville Syrj_l_" <[email protected]>
Cc: Imre Deak <[email protected]>
Cc: Manasi Navare <[email protected]>
Cc: Gwan-gyeong Mun <[email protected]>
Cc: Lucas De Marchi <[email protected]>
Cc: Sean Paul <[email protected]>
Signed-off-by: Ankit Nautiyal <[email protected]>
Reviewed-by: Swati Sharma <[email protected]>
Signed-off-by: Anshuman Gupta <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit 88a9c5485c48ab60c89612a17fc89f4162bbdb9d)
Signed-off-by: Jani Nikula <[email protected]>