u-boot-linaro: Fix build error

Fix this u-boot-linaro build error related to soft-float support:

 arm-poky-linux-gnueabi-ld: error: u-boot uses VFP register arguments,
/media/data/fb/majo/toolchain/poky/build/tmp/sysroots/arndale-octa/usr/
lib/arm-poky-linux-gnueabi/4.9.0/libgcc.a(_udivdi3.o) does not
 arm-poky-linux-gnueabi-ld: failed to merge target specific data of file
/media/data/fb/majo/toolchain/poky/build/tmp/sysroots/arndale-octa/usr/
lib/arm-poky-linux-gnueabi/4.9.0/libgcc.a(_udivdi3.o)
 make: *** [u-boot] Erro1
 ERROR: oe_runmake failed