fix regression in tcsetattr on all mips archs

revert commit 8c316e9e49d37ad92c2e7493e16166a2afca419f. it was wrong
and does not match how the kernel API works.

format mips bits/termios.h consistently mips64 and n32 versions

with this change, all three files are identical.

fix TCS* definitions in mips termios.h

these were incorrectly using the generic definitions.

fix mips termios.h macro exposure/namespace issues

same changes to the defined macros as in powerpc and generic bits.

fix namespace violations in termios.h, at least mostly

the fix should be complete on archs that use the generic definitions
(i386, arm, x86_64, microblaze), but mips and powerpc have not been
checked thoroughly and may need more fixes.

fix termios constants on mips

initial version of mips (o32) port, based on work by Richard Pennington (rdp)

basically, this version of the code was obtained by starting with
rdp's work from his ellcc source tree, adapting it to musl's build
system and coding style, auditing the bits headers for discrepencies
with kernel definitions or glibc/LSB ABI or large file issues, fixing
up incompatibility with the old binutils from aboriginal linux, and
adding some new special cases to deal with the oddities of sigaction
and pipe syscall interfaces on mips.

at present, minimal test programs work, but some interfaces are broken
or missing. threaded programs probably will not link.