EFI: Make installer EFI aware

[YOCTO #1919]

Create a basic EFI installer script modeled after the existing installer
and add it to a new initramfs-live-install-efi recipe. Update the
init-live.sh script to distinguish between LABEL=install and
LABEL=install-efi and select the appropriate script. Add the efi
installer to core-image-minimal-initramfs.

Update grub-efi.bbclass to use "LABEL=install-efi" when it detects a
label of "install". This is clearly not ideal, but a proper fix would
involve decoupling the LABELS assignment from the image-live.bbclass
usage of SYSLINUX_LABELS. We should be able to address that in a
follow-on clean-up series.

V2: Include missing initramfs-live-install-efi_1.0.bb
V3: Rebase after Radu's console_params fix

(From OE-Core rev: 4bce3417917a3e88ba6529db394525fba82e0699)

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/grub-efi.bbclass

@@ -99,6 +99,8 @@ python build_grub_cfg() {
         bb.data.update_data(localdata)
 
         cfgfile.write('\nmenuentry \'%s\'{\n' % (label))
+        if label == "install":
+            label = "install-efi"
         cfgfile.write('linux /vmlinuz LABEL=%s' % (label))
 
         append = localdata.getVar('APPEND', True)