plymouth: remove unused patch file

* it was removed from SRC_URI in:
  https://git.openembedded.org/meta-openembedded/commit/?id=479b1455e37d49bc24f709bd2284effdb92686ab

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-core/plymouth/files/0001-systemd-switch-to-KillMode-mixed.patch

@@ -1,43 +0,0 @@
-From 9d0f8b2e7bc2d1d2b0900fcdf119bb9a2cc4f474 Mon Sep 17 00:00:00 2001
-From: Ray Strode <rstrode@redhat.com>
-Date: Tue, 25 Aug 2020 10:49:11 -0400
-Subject: [PATCH] systemd: switch to KillMode=mixed
-
-KillMode=none is deprecated, so we need to stop using it.
-
-For now, use `KillMode=mixed` and `IgnoreOnIsolate=true` instead.
-
-In the future, we should change plymouth to be able to exit and
-start again without restarting the active animation, but that's
-going to require some effort.
-
-https://gitlab.freedesktop.org/plymouth/plymouth/-/issues/123
-
-Upstream-Status: Backport [https://gitlab.freedesktop.org/plymouth/plymouth/-/commit/9d0f8b2e7bc2d1d2b0900fcdf119bb9a2cc4f474]
-
-Signed-off-by: Mingli Yu <mingli.yu@windriver.com>
----
- systemd-units/plymouth-start.service.in | 3 ++-
- 1 file changed, 2 insertions(+), 1 deletion(-)
-
-diff --git a/systemd-units/plymouth-start.service.in b/systemd-units/plymouth-start.service.in
-index 3d00cc6..830a62d 100644
---- a/systemd-units/plymouth-start.service.in
-+++ b/systemd-units/plymouth-start.service.in
-@@ -6,11 +6,12 @@ After=systemd-vconsole-setup.service systemd-udev-trigger.service systemd-udevd.
- Before=systemd-ask-password-plymouth.service
- ConditionKernelCommandLine=!plymouth.enable=0
- ConditionVirtualization=!container
-+IgnoreOnIsolate=true
- 
- [Service]
- ExecStart=@PLYMOUTH_DAEMON_DIR@/plymouthd --mode=boot --pid-file=@plymouthruntimedir@/pid --attach-to-session
- ExecStartPost=-@PLYMOUTH_CLIENT_DIR@/plymouth show-splash
- Type=forking
- RemainAfterExit=yes
--KillMode=none
-+KillMode=mixed
- SendSIGKILL=no
--- 
-2.17.1
-