treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MIPS: Sibyte: Migrate to new platform makefile style.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] Use -Werror on subdirectories which build cleanly.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] Kill redundant EXTRA_AFLAGS

Many Makefiles in arch/mips have EXTRA_AFLAGS := $(CFLAGS) line. This
is redundant while AFLAGS contains $(cflags-y) and any options only
listed in CFLAGS (not in cflags-y) should be unnecessary for asm
sources.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] Rewrite all the assembler interrupt handlers to C.

Saves like 1,600 lines of code, is way easier to debug, compilers
frequently do a better job than the cut and paste type of handlers many
boards had. And finally having all the stuff done in a single place
also means alot of bug potencial for the MT ASE is gone.

The only surviving handler in assembler is the DECstation one; I hope
Maciej will rewrite it.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Add support for BCM1480 family of chips.

- Kconfig and Makefile changes
- arch/mips/sibyte/bcm1480/
- changes to sibyte common code to support 1480

Signed-Off-By: Andy Isaacson <adi@broadcom.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>