spi: meson-spicc: Fix error handling in meson_spicc_probe()

If devm_spi_register_master() fails in meson_spicc_probe(),
spicc->core is left undisabled. The patch fixes that.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Mark Brown <broonie@kernel.org>