spi: spidev_test: Remove break after exit statement

When call print_usage() in parse_opts(), it will exit directly.
Since break is not useful after exit statement, remove it.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/1581567368-8055-1-git-send-email-yangtiezhu@loongson.cn


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