drm/amd: Add a new helper for loading/validating microcode

All microcode runs a basic validation after it's been loaded. Each
IP block as part of init will run both.

Introduce a wrapper for request_firmware and amdgpu_ucode_validate.
This wrapper will also remap any error codes from request_firmware
to -ENODEV.  This is so that early_init will fail if firmware couldn't
be loaded instead of the IP block being disabled.

Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>