initrdscripts: handle mmc device as installer medium
Platforms which have the capability of using the MMC as an
installer medium will present the same MMC device as an
installation candidate. This happens because the MMC
devices appear as mmcblk<X> and the current script strips
up the <X> which is needed to identify an MMC device
uniqely.
This patch now updates the way device identifier stripping
is done and handles the exclusion of installer device from
installation candidates more generically.
Signed-off-by: Awais Belal <awais_belal@mentor.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
