luv-live-image: Reduce grub timeout and add quiet kernel parameter

We don't need to wait for the default 10 seconds before booting the luv
kernel since the most common use case is people wanting to run the luv
tests, rather than interrupting the grub boot to inject some debugging
options.

Also add the "quiet" kernel parameter to reduce the noise of kernel
messages on the console.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Enable support for VESA framebuffer

Not all EFI machines support efifb so enable the vesa framebuffer driver
which should hopefully allow us to display the splash image on those
machines lacking GOP support.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
luv-test-manager: Add kernel parameter to disable luv tests

Adding "noluv" to the kernel command line will skip the luv tests on
boot, which is useful in conjunction with "psplash=false" to boot the
machine without displaying the splash screen.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>