arch-mips.inc: Change definition of TRANSLATED_TARGET_ARCH

arch-mips.inc: Change definition of TRANSLATED_TARGET_ARCH

[YOCTO #7230]

In certain system configurations TRANSLATED_TARGET_ARCH will not
expand in the right order for gcc-cross-candian-mips64n32 to be
generated properly.

This will cause SDKs to fail to generate properly.

Changing the global definition of TRANSLATED_TARGET_ARCH always
expands the ABIEXTENSION, which causes the OVERRIDES to pick it up
as well.  This effectively defines a new class of overrides for the 'n32'.

The side effect is that we need to duplicate some mips64 overrides, and
redefine others that were previously 'n32' or 'mips64' exclusive to have
the correct semantics.

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>