spi: efm32: Clean up non-DT paths
spi: efm32: Clean up non-DT paths

This is a DT-only driver, so remove all non-DT paths.
of_gpio_named_count() may fail, thus also add checking it's return value.
efm32_spi_probe_dt() never fails, make it return void.

Signed-off-by: Axel Lin <b6ffd6973e972cb999e8e535ab74da7fee0c035f@ingics.com>
Acked-by: Uwe Kleine-König <181323dd666a182bc2d953e52d0ac3ab54cd8391@pengutronix.de>
Signed-off-by: Mark Brown <b51b9a92386687a9ac927cebfa0f978adeb8cea5@linaro.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs