drm/amd/display (gcc13): fix enum mismatch

rn_vbios_smu_set_dcn_low_power_state() produces a valid warning with
gcc-13:
  drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr_vbios_smu.c:237:6: error: conflicting types for 'rn_vbios_smu_set_dcn_low_power_state' due to enum/integer mismatch; have 'void(struct clk_mgr_internal *, enum dcn_pwr_state)'
  drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr_vbios_smu.h:36:6: note: previous declaration of 'rn_vbios_smu_set_dcn_low_power_state' with type 'void(struct clk_mgr_internal *, int)'

I.e. the type of the 2nd parameter of
rn_vbios_smu_set_dcn_low_power_state() in the declaration is int, while
the definition spells enum dcn_pwr_state. Synchronize them to the
latter (and add a forward enum declaration).

Cc: Martin Liska <[email protected]>
Cc: Harry Wentland <[email protected]>
Cc: Leo Li <[email protected]>
Cc: Rodrigo Siqueira <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: "Christian König" <[email protected]>
Cc: "Pan, Xinhui" <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: [email protected]
Cc: [email protected]
Reviewed-by: Harry Wentland <[email protected]>
Signed-off-by: Jiri Slaby (SUSE) <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

0 files changed, 0 insertions, 0 deletions