The test is actually using grub-efi not systemd-boot so
remove it completely. systemd-boot will be tested via uki.py
tests.

(From OE-Core rev: 542ea853bb194629d23e1db9c05e25181bfce145)

Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>