init-install-efi.sh: improve hard drive searching process

(This patch was originally done against init-install.sh in
OE-Core rev 358f0584d779825307eec08c023b5ff14e72cf9e)

Previously, only unremovable hard drives are searched and are treated
as candidates of target disks to intall into.

However, it's possible that we're going to install the live image into
a removable media such as an USB. This patch enables this possibility.

In addition, this patch presents more information about the hard drives
so that user may have more knowledge about which hard drive they are
going to install their image into.

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>
init-install-efi.sh: fix to handle the boot partition correctly

(This patch was originally done against init-install.sh in
OE-Core rev aa67b1333b4774e1845f562085f7048df65a644f)

Previously, the boot partition was created for the target hard drive
but there was no corresponding entry for it in /etc/fstab. Besides,
even if the boot partition was mounted, it would just result in odd
directory hierarchy like /boot/boot/grub. However, what we really need
is /boot/grub. This patch fixes this problem.

Besides, for future maintance work, this patch also renames some of the
intermediate directories. It uses more descriptive names like /tgt_root
and /src_root. The name of /ssd is dropped.

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>
init-install-efi.sh: Verify /sys based files exist before displaying them

Some mmc cards do not have all the data files in /sys/block
populated.  Check for existence before displaying the files
to avoid erroring out of the install process.

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>
init-install.sh: Verify /sys based files exist before displaying them

Some mmc cards do not have all the data files in /sys/block
populated.  Check for existence before displaying the files
to avoid erroring out of the install process.

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>
gstreamer1.0-omx: Use variables for CORE_NAME processing.

Use the "libdir" and "sysconfdir" variables rather than
hard-coding "/usr/lib" and "/etc".

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>