package/kvm-unit-tests: fix powerpc64 PHDR seg err

package/kvm-unit-tests: fix powerpc64 PHDR seg err

Upstream comment: "Let's introduce some fake PHDRs
to the linker script to get this working again."

Fixes:
(next) http://autobuild.buildroot.net/results/ae091dbcb155e63c208ce5adb289807cee83e28d/
(master) http://autobuild.buildroot.net/results/ef0/ef0b044802c54a697d8bffb28eba08cf9ce44f4c/
(2021.02.x) http://autobuild.buildroot.net/results/044/04495aa23ce51c48b9b850890453abded85dc477/
(2021.05.x) http://autobuild.buildroot.net/results/0fa/0fa94f1f930aa16cec3bc96e64bc57b460238a0a/

[Cherry-picked upstream]
5126732d73aa75a0bc84f898042bfe35640624b8

Signed-off-by: Matthew Weber <matthew.weber@collins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>