feat(fiptool): handle FIP in a disk partition

feat(fiptool): handle FIP in a disk partition

When FIP is programmed in a disk partition, fiptool cannot be used
directly; this forces the user to temporarily copy the partition
to a file, apply fiptool and copy back the file. This is caused by
fstat() that returns zero file size on a block special file, thus
making fiptool commands info, update, unpack and remove to exit.

For either Linux host or Linux target, recover the partition size
with ioctl() and use it as FIP file size. E.g.:
	fiptool info /dev/disk/by-partlabel/fip-a
	fiptool info /dev/mtdblock4

While there, rework two identical error log messages to provide
more details about the failure and update the date in copyright.

Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Change-Id: I7cab60e577422d94c24ba7e39458f58bcebc2336