fat16: fix read and remove debug messages

* fat16 code had old debug prints, get rid of that
* yaboot tried reading a file beyond the size of file, fix read
  routine to override and read only till the file-size

Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
boot from disk having chrp-boot file

SLES when creating an LVM, creates a boot partition with
CHRP-BOOT. This was only being handled for CDROM case. Add this for
the hard-disk as well.

Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Add boot menu support

This patch adds boot menu support to SLOF. When boot menu is enabled from qemu
commandline with '-boot menu=on', on pressing F12 key it displays the list of
devices to boot from and waits for user's input. This is in line with x86 qemu
bios feature.

Signed-off-by: Avik Sil <aviksil@linux.vnet.ibm.com>
Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>