riscv64: use earlycon=sbi on command line

With current kernel we need to specify the SBI driver
for the early console to work.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

live-build/ubuntu-cpc/hooks.d/base/riscv64/grub/10_cmdline.cfg

@@ -1,4 +1,4 @@
 # Booting on many riscv64 systems is slow. Let the user view progress.
 # For minimum output use
 # GRUB_CMDLINE_LINUX_DEFAULT="quiet"
-GRUB_CMDLINE_LINUX_DEFAULT="efi=debug earlycon"
+GRUB_CMDLINE_LINUX_DEFAULT="efi=debug earlycon=sbi"

live-build/ubuntu-cpc/hooks.d/base/riscv64/u-boot-menu/10_cmdline.conf

@@ -1 +1 @@
-U_BOOT_PARAMETERS="ro efi=debug earlycon"
+U_BOOT_PARAMETERS="ro efi=debug earlycon=sbi"