The hw i2c engines are disabled by default as the
current implementation is still experimental. Print
a warning when users enable it so that it's obvious
when the option is enabled.
v2: check for non-0 rather than 1
Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>