drm/amd/display: increased min_dcfclk_mhz and min_fclk_mhz

drm/amd/display: increased min_dcfclk_mhz and min_fclk_mhz

[why]
Originally, PMFW said min FCLK is 300Mhz, but min DCFCLK can be increased
to 400Mhz because min FCLK is now 600Mhz so FCLK >= 1.5 * DCFCLK hardware
requirement will still be satisfied. Increasing min DCFCLK addresses
underflow issues (underflow occurs when phantom pipe is turned on for some
Sub-Viewport configs).

[how]
Increasing DCFCLK by raising the min_dcfclk_mhz

Reviewed-by: Chaitanya Dhere <chaitanya.dhere@amd.com>
Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Sohaib Nadeem <sohaib.nadeem@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>