gpio: stmpe: make it explicitly non-modular

gpio: stmpe: make it explicitly non-modular

The Kconfig currently controlling compilation of this code is:

drivers/gpio/Kconfig:config GPIO_STMPE
drivers/gpio/Kconfig:   bool "STMPE GPIOs"

...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.

We explicitly disallow a driver unbind, since that doesn't have a
sensible use case anyway, and it allows us to drop the ".remove"
code for non-modular drivers.

Curiously, this driver was using subsys_initcall since day one, so
we don't have the "normal" module_init replacement in this change
like we've done in other similar driver updates.

We also delete the MODULE_LICENSE tag etc. since all that information
is already contained at the top of the file in the comments.

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Rabin Vincent <rabin.vincent@stericsson.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>