drivers/tty: make serial/mvebu-uart.c explicitly non-modular
The Kconfig currently controlling compilation of this code is:
drivers/tty/serial/Kconfig:config SERIAL_MVEBU_UART
drivers/tty/serial/Kconfig: bool "Marvell EBU serial port support"
...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.
Since the code wasn't using module_init to begin with, 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.