drm/amd/display: Add kdoc entry for 'program_isharp_1dlut' in 'dpp401_dscl_program_isharp'

Added a descriptor for the 'program_isharp_1dlut' parameter, which is a
flag used to determine whether to program the isharp 1D LUT.

Fixes the below with gcc W=1:
drivers/gpu/drm/amd/amdgpu/../display/dc/dpp/dcn401/dcn401_dpp_dscl.c:963: warning: Function parameter or struct member 'program_isharp_1dlut' not described in 'dpp401_dscl_program_isharp'

Cc: Tom Chung <chiahsuan.chung@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Roman Li <roman.li@amd.com>
Cc: Alex Hung <alex.hung@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dpp/dcn401/dcn401_dpp_dscl.c

@@ -951,6 +951,7 @@ static void dpp401_dscl_set_isharp_filter(
  *
  * @dpp_base: High level DPP struct
  * @scl_data: scalaer_data info
+ * @program_isharp_1dlut: flag to program isharp 1D LUT
  * @bs_coeffs_updated: Blur and Scale Coefficients update flag
  *
  * This is the primary function to program isharp