syslinux: fix stripped file warnings

syslinux: fix stripped file warnings

Fix the following package warnings:
WARNING: File '/usr/bin/memdiskfind' from syslinux was already stripped, this will prevent future debugging!
WARNING: File '/usr/bin/syslinux' from syslinux was already stripped, this will prevent future debugging!
WARNING: File '/usr/bin/gethostip' from syslinux was already stripped, this will prevent future debugging!
WARNING: File '/usr/bin/isohybrid' from syslinux was already stripped, this will prevent future debugging!

(From OE-Core rev: 90bf61226d1bebd846ad9dc028affc334862e794)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>