spi: atmel: print version only after successful registration

Don't print the version at the beginning of atmel_spi_probe(). This avoids
spamming the log whenever a deferred probe runs.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Mark Brown <broonie@kernel.org>