msm: mdss: Don't allocate memory dynamically for small layer buffers

There's no reason to dynamically allocate memory for a single, small
struct instance (output_layer) when it can be allocated on the stack.
Additionally, layer_list and validate_info_list are limited by the
maximum number of layers allowed, so they can be replaced by stack
allocations.

Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>