ixp4xx: upgrade: don't copy extra binaries

hexdump is already added to new temporary file system while less is not used at
all. While at it, remove some trailing whitespaces.

Signed-off-by: Luka Perkov <luka@openwrt.org>
CC: Imre Kaloz <kaloz@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39181 3c298f89-4303-0410-b956-a3cf2f4a3e73