build(plat/marvell): add descriptions why some checks are required

This change adds just comments why some checks are required. They check
that ENV variables and external repos are correctly set for TF-A builds.

Signed-off-by: Pali Rohár <pali@kernel.org>
Change-Id: I2f8af5061411c0c92d3875917f4d97b60dc2cf10
diff --git a/plat/marvell/armada/a8k/common/ble/ble.mk b/plat/marvell/armada/a8k/common/ble/ble.mk
index 87e2ce0..e41ab3e 100644
--- a/plat/marvell/armada/a8k/common/ble/ble.mk
+++ b/plat/marvell/armada/a8k/common/ble/ble.mk
@@ -28,6 +28,7 @@
 $(BLE_OBJS): $(MV_DDR_LIB)
 
 $(MV_DDR_LIB): FORCE
+	# Do not remove! Following checks are required to ensure correct TF-A builds, removing these checks leads to broken TF-A builds
 	$(if $(value MV_DDR_PATH),,$(error "Platform '$(PLAT)' for BLE requires MV_DDR_PATH. Please set MV_DDR_PATH to point to the right directory"))
 	$(if $(wildcard $(value MV_DDR_PATH)/*),,$(error "'MV_DDR_PATH=$(value MV_DDR_PATH)' was specified, but '$(value MV_DDR_PATH)' directory does not exist"))
 	$(if $(shell git -C $(value MV_DDR_PATH) rev-parse --show-cdup 2>&1),$(error "'MV_DDR_PATH=$(value MV_DDR_PATH)' was specified, but '$(value MV_DDR_PATH)' does not contain valid mv-ddr-marvell git repository"))