On UEFI-enabled systems, the location of grub.cfg is different.
While at it, add ttyAMA0 (aarch64 PL011 serial device) console
to default kernel cmdline.
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
Change-Id: I98b709587bfaef21134da45dfa227673c2b10678