uboot-at91: fix build after fpu activation

neon and VFPv4 support is added to this target and uboot-at91 build
fails due to TARGET_CFLAGS -mfloat-abi set to hard. as a fix, setting
uboot-at91 CFLAGS -mfloat-abi=soft.

Fixes: 01cc6bd495 ("at91: sama5: activate fpu")
Signed-off-by: Sandeep Sheriker Mallikarjun <sandeepsheriker.mallikarjun@microchip.com>

package/boot/uboot-at91/Makefile

@@ -88,7 +88,7 @@ UBOOT_TARGETS := \
 define Build/Compile
 	+$(MAKE) $(PKG_JOBS) -C $(PKG_BUILD_DIR) \
 		CROSS_COMPILE=$(TARGET_CROSS) \
-		KCFLAGS="$(filter-out -fstack-protector, $(TARGET_CFLAGS))"
+		KCFLAGS="$(filter-out -fstack-protector -mfloat-abi=hard, $(TARGET_CFLAGS)) -mfloat-abi=soft" 
 endef
 
 $(eval $(call BuildPackage/U-Boot))