pinctrl: stm32: make explicitly non-modular

The Kconfig currently controlling compilation of this code is:

drivers/pinctrl/stm32/Kconfig:config PINCTRL_STM32F429
drivers/pinctrl/stm32/Kconfig:  bool "STMicroelectronics STM32F429 pin control" if COMPILE_TEST && !MACH_STM32F429

...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 translates to device_initcall in the non-modular
case, 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
is already contained at the top of the file in the comments.

Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: linux-gpio@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>