Platform: Refactor fvp_sse300 CMakeList.txt files

Refactor mps2 and mps3 fvp_sse300 CMakeList.txt files to match
directory structure for better readability

Signed-off-by: Marton Berke <marton.berke@arm.com>
Change-Id: I67767fbd3dcc6125d1fa36dd3553d78e68982c39
2 files changed