fsi: aspeed: Add trace points

These trace points help with debugging the FSI master. They show the low
level reads, writes and error states of the master.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20191108051945.7109-11-joel@jms.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>