Remove all unused bitfields and macros. Convert the remaining
bitfields to use __BITFIELD_FIELD instead of #ifdef.

[ralf@linux-mips.org: Add inclusions of <uapi/asm/bitfield.h> as necessary.]
Signed-off-by: Steven J. Hill <steven.hill@cavium.com>
Acked-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15403/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>