refactor: re-use run config fragments for TC platform variants

Several platforms have multiple variants, yet, they share most of the
software binaries and hence can utilize common run fragments. This
removes the need to maintain run fragments on per-variant basis.

We do this by introducing an environment variable `plat_variant` that
is populated from build parameter `TARGET_PLATFORM`

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: I4218942b33dd32440a1ce9f7e78627bbe6710a69
diff --git a/model/base-aemva-common.sh b/model/base-aemva-common.sh
index 01b6b20..5d31b91 100644
--- a/model/base-aemva-common.sh
+++ b/model/base-aemva-common.sh
@@ -17,6 +17,8 @@
 reset_var aarch64_only
 reset_var aarch32
 
+reset_var plat_variant
+
 #------------ GIC configuration --------------
 
 # GICv2 compatibility is not supported and GICD_CTLR.ARE_* is always one