gpio: sx150x: fix implicit assumption module.h is present

This file is currently getting module.h from a global gpio header
and it will faii to build once we remove module.h from that.

However, the driver is controlled with the following Kconfig:

drivers/gpio/Kconfig:config GPIO_SX150X
drivers/gpio/Kconfig:   bool "Semtech SX150x I2C GPIO expander"

and hence the two lines of MODULE_DEVICE_TABLE are no-ops that
can simply be deleted.

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: linux-gpio@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>