add uImage kernel-imagetype for fsp2

in a63de4a41 uimage class was added for fsp2 board
but that was not enough to make an uImage binary.

Signed-off-by: Ivan Mikhaylov <ivan@de.ibm.com>
Change-Id: I605ce5a5f78a6b3f98429e2eaae9457811e8e506
1 file changed