gpio: sx150x: make explicitly non-modular

gpio: sx150x: make explicitly non-modular

The Kconfig currently controlling compilation of this code is:

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

...meaning that it currently is not being built as a module by anyone.

Lets remove the modular code that is essentially orphaned, so that
when reading the driver there is no doubt it is builtin-only.

Since module_init was not in use by this code, the init ordering
remains unchanged with this commit.

We also delete the MODULE_LICENSE tag etc. since all that information
was (or is now) contained at the top of the file in the comments.

Cc: Gregory Bean <gbean@codeaurora.org>
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>