fix(coverity): temporarily exclude Arm FPGA from Coverity analysis

Arm FPGA platform build is failing due to increased size of the BL31 binary
as a result of spectre-bhb mitigation, causing tf-coverity job to fail.
This patch temporarily excludes Arm FPGA platfom until the issue is resolved.

Signed-off-by: Zelalem Aweke <zelalem.aweke@arm.com>
Change-Id: Ic7696a1062d8e41fee7aabcb25565386fe622174
2 files changed