Revert "Enable serial console in default grub"

This reverts commit 7773f82.

After ISO installation in real hardware and reboot,
the boot process appears to be "stucking" in
"dracut: Switching root".

see #1

revert the commit resolves the issue, I suspect maybe
the output after "dractu: Switching root" is directed
to serial console? anyway revert this change temporarily.
flash image build still need to have serial console access
for better user experience when trying flash image in KVM/Libvirt
virtual environment.

Signed-off-by: Vincent Li <[email protected]>

config/grub2/default

@@ -1,8 +1,6 @@
 GRUB_TIMEOUT=5
 GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
 GRUB_DEFAULT=saved
-GRUB_CMDLINE_LINUX="rd.auto panic=10 console=tty0 console=ttyS0,115200n8"
-GRUB_TERMINAL=serial
-GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop==1"
+GRUB_CMDLINE_LINUX="rd.auto panic=10"
 GRUB_DISABLE_RECOVERY="true"
 GRUB_BACKGROUND="/boot/grub/splash.png"