spi: gpio: Look for a device node instead of match

spi: gpio: Look for a device node instead of match

This driver doesn't do anything with the match for the device node. The
logic is the same as looking to see if a device node exists or not
because this driver wouldn't probe unless there is a device node match
when the device is created from DT. Just test for the presence of the
device node to simplify and avoid referencing a potentially undefined
match table when CONFIG_OF=n.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: <linux-spi@vger.kernel.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20191004214334.149976-9-swboyd@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>