chore(rCS posix): move param override through env var after airframe selection (#26193)

Signed-off-by: Beniamino Pozzan <beniamino.pozzan@gmail.com>

ROMFS/px4fmu_common/init.d-posix/rcS

@@ -126,15 +126,6 @@ then
 	set AUTOCNF yes
 fi
 
-# Allow overriding parameters via env variables: export PX4_PARAM_{name}={value}
-env | while IFS='=' read -r line; do
-  value=${line#*=}
-  name=${line%%=*}
-  case $name in
-    "PX4_PARAM_"*) param set "${name#PX4_PARAM_}" "$value" ;;
-  esac
-done
-
 # multi-instance setup
 # shellcheck disable=SC2154
 param set MAV_SYS_ID $((px4_instance+1))
@@ -238,6 +229,15 @@ then
 	exit 1
 fi
 
+# Allow overriding parameters via env variables: export PX4_PARAM_{name}={value}
+env | while IFS='=' read -r line; do
+  value=${line#*=}
+  name=${line%%=*}
+  case $name in
+    "PX4_PARAM_"*) param set "${name#PX4_PARAM_}" "$value" ;;
+  esac
+done
+
 dataman start
 
 # only start the simulator if not in replay mode, as both control the lockstep time