mfd: altera-a10sr: Make it explicitly non-modular

The Kconfig currently controlling compilation of this code is:

drivers/mfd/Kconfig:config MFD_ALTERA_A10SR
drivers/mfd/Kconfig:    bool "Altera Arria10 DevKit System Resource chip"

...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 builtin_driver() uses the same init level priority as
module_spi_driver() the init ordering remains unchanged with
this commit. [Note that there is no builtin_spi_driver macro,
so we open-code what it would be via builtin_driver().]

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: Thor Thayer <tthayer@opensource.altera.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>