hv: remove "i915.enable_initial_modeset"

removed "i915.enable_initial_modeset" sos kernel cmdline option from acrn.conf

Tracked-On: #1982 
Signed-off-by: ailun258 <ailin.yang@intel.com>

Author: ailun258

hypervisor/bsp/uefi/clearlinux/acrn.conf

@@ -1,3 +1,3 @@
 title The ACRN Service OS
 linux   /EFI/org.clearlinux/kernel-org.clearlinux.iot-lts2018-sos.4.19.0-16
-options console=tty0 console=ttyS0 i915.nuclear_pageflip=1 root=PARTUUID=<UUID of rootfs partition> rw rootwait ignore_loglevel no_timer_check consoleblank=0 i915.tsd_init=7 i915.tsd_delay=2000 i915.avail_planes_per_pipe=0x01010F i915.domain_plane_owners=0x011111110000 i915.enable_guc_loading=0 i915.enable_guc_submission=0 i915.enable_preemption=1 i915.context_priority_mode=2 i915.enable_gvt=1 i915.enable_initial_modeset=1 i915.enable_guc=0 hvlog=2M@0x1FE00000
+options console=tty0 console=ttyS0 i915.nuclear_pageflip=1 root=PARTUUID=<UUID of rootfs partition> rw rootwait ignore_loglevel no_timer_check consoleblank=0 i915.tsd_init=7 i915.tsd_delay=2000 i915.avail_planes_per_pipe=0x01010F i915.domain_plane_owners=0x011111110000 i915.enable_guc_loading=0 i915.enable_guc_submission=0 i915.enable_preemption=1 i915.context_priority_mode=2 i915.enable_gvt=1 i915.enable_guc=0 hvlog=2M@0x1FE00000