package/uclibc: fixup e500mc support

The e500mc core has a classic FPU, SPE is a bad word.
See: http://en.wikipedia.org/wiki/PowerPC_e500#e500mc



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>