Remove MIPS architecture

The MIPS architecture port has been added 5+ years ago in order to
support a Chrome OS project that ended up going nowhere. No other board
has used it since and nobody is still willing or has the expertise and
hardware to maintain it. We have decided that it has become too much of
a mainenance burden and the chance of anyone ever reviving it seems too
slim at this point. This patch eliminates all MIPS code and
MIPS-specific hacks.

Change-Id: I5e49451cd055bbab0a15dcae5f53e0172e6e2ebe
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34919
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/cbfstool/cbfs.h

@@ -65,7 +65,7 @@ struct cbfs_header {
 #define CBFS_ARCHITECTURE_X86      0x00000001
 #define CBFS_ARCHITECTURE_ARM      0x00000010
 #define CBFS_ARCHITECTURE_AARCH64  0x0000aa64
-#define CBFS_ARCHITECTURE_MIPS     0x00000100
+#define CBFS_ARCHITECTURE_MIPS     0x00000100	/* deprecated */
 #define CBFS_ARCHITECTURE_RISCV    0xc001d0de
 #define CBFS_ARCHITECTURE_PPC64    0x407570ff