avr32: remove .note.gnu.build-id section when making vmlinux.bin

This patch will remove the section .note.gnu.build-id added in binutils
2.18 from the vmlinux.bin binary. Not removing this section results in a
huge multiple gigabyte binary and likewize large uImage.

Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>