linux-yocto: correct qemumips64el definition

linux-yocto: correct qemumips64el definition

The big endian mips definition was used as the basis for the little
endian machine. Unfortunatey, the KMACHINE definitions were not fully
cleared, so big endian builds will match on the 'le' variant .. and
break.

We drop the BE machine definitions from the LE variant and we are fixed.

(From OE-Core rev: 863e520059cdc96817ec87983d1e036f291bf37c)

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>