meta-ti-bsp: ti-sgx-ddk-um: drop systemd service workaround

meta-ti-bsp: ti-sgx-ddk-um: drop systemd service workaround

Latest TI graphics package uses udev rules to initialize the driver
and does not install legacy SysVinit rc.pvr script unless udev isn't
available. No need for systemd service workaround anymore.

Bug-AGL: SPEC-4723

Change-Id: I3ce5d270357578086152d87fb2cf91512691e1a9
Signed-off-by: Denys Dmytriyenko <denys@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/28740
Tested-by: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>