drm/komeda: Add komeda_crtc_mode_valid/fixup

komeda_crtc_mode_valid compares the input mode->clk with main engine clk
and AXI clk, and reject the mode if the required pixel clk can not be
satisfied by main engine clk and AXI-clk.

Signed-off-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>