The contents of macros are parsed by the assembler before conditions
have been tested. This causes assembly errors when using IP-specific
instructions in the IP-unified trap handler.

Add a preprocessing step to filter IP-specific code.

Also guard a Navi1x-specific instruction (no effect on Sienna_Cichlid).
Signed-off-by: Jay Cornwall <jay.cornwall@amd.com>
Reviewed-by: Yong Zhao <Yong.Zhao@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>