We set WC memtype for aper_base but don't check return value
of arch_io_reserve_memtype_wc(). Be more defensive and return
early on error.
Signed-off-by: NNirmoy Das <nirmoy.das@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>