gpio: bcm-kona: make explicitly non-modular

The Kconfig currently controlling compilation of this code is:

config GPIO_BCM_KONA
        bool "Broadcom Kona GPIO"

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

Lets remove the couple traces of modularity so that when reading the
driver there is no doubt it is builtin-only.

Since module_platform_driver() uses the same init level priority as
builtin_platform_driver() the init ordering remains unchanged with
this commit.

Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.

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: Ray Jui <rjui@broadcom.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: bcm-kernel-feedback-list@broadcom.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>