ci(juno): add build config with SPMC_AT_EL3

Since patch [0], juno supports StandaloneMm with SPMC_AT_EL3.
add ci build test with SPMC_AT_EL3 in juno platform.

Link: https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/38743/29 [0]
Change-Id: I53cbd6e3cb22eb52f146e3e767c2e8965a04ce8f
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
2 files changed