spi: tegra: Fix missing IRQ check in tegra_slink_probe()

This func misses checking for platform_get_irq()'s call and may passes the
negative error codes to request_irq(), which takes unsigned IRQ #,
causing it to fail with -EINVAL, overriding an original error code.

Fix this by stop calling request_irq() with invalid IRQ #s.

Fixes: dc4dc360

 ("spi: tegra: add spi driver for SLINK controller")
Signed-off-by: Zhang Shurong <zhang_shurong@foxmail.com>
Reviewed-by: Helen Koike <helen.koike@collabora.com>
Link: https://lore.kernel.org/r/tencent_73FCC06A3D1C14EE5175253C6FB46A07B709@qq.com


Signed-off-by: Mark Brown <broonie@kernel.org>