grub2: change armvirt reference to armsr

The armvirt target has been renamed to armsr (Arm SystemReady),
so the GRUB configuration also needs to change.

Signed-off-by: Mathew McBride <[email protected]>

package/boot/grub2/Makefile

@@ -41,7 +41,7 @@ endef
 
 Package/grub2=$(call Package/grub2/Default,x86,pc)
 Package/grub2-efi=$(call Package/grub2/Default,x86,efi)
-Package/grub2-efi-arm=$(call Package/grub2/Default,armvirt,efi)
+Package/grub2-efi-arm=$(call Package/grub2/Default,armsr,efi)
 
 define Package/grub2-editenv
   CATEGORY:=Utilities