MIPS: copy pic32.h header file from asm/mach-pic32/ to include/platform-data/

MIPS: copy pic32.h header file from asm/mach-pic32/ to include/platform-data/

There are currently some pic32 MIPS drivers that are in tree, and are
only configured to be compiled on the pic32 platform. There's a risk of
breaking some of these drivers when migrating drivers away from legacy
APIs. It happened to me with a pic32 clk driver.

Let's go ahead and copy the MIPS pic32.h header to
include/linux/platform_data/, and make a minor update to allow compiling
this on other architectures. This will make it easier, and cleaner to
enable COMPILE_TEST for some of these pic32 drivers.

The asm variant of the header file will be dropped once all drivers have
been updated.

Link: https://lore.kernel.org/linux-clk/CABx5tq+eOocJ41X-GSgkGy6S+s+Am1yCS099wqP695NtwALTmg@mail.gmail.com/T/
Signed-off-by: Brian Masney <bmasney@redhat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>