uboot-phytec

malta: correct tcl script path in README.malta

README.malta referred to board/malta, but malta has now been moved
within board/imgtec/, so correct the path.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Cc: Paul Burton <paul.burton@imgtec.com>