refactor: delete build option 'enable_vhe'

These set of changes are making VHE enabled by default. This means, the
'enable_vhe' configuration flag is not needed in the Hafnium build
targets.

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: I35365ea932587d75e3a3ef913adc04b13db23001
diff --git a/BUILD.gn b/BUILD.gn
index 3080ec7..4406c14 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -70,7 +70,6 @@
     pl011_base_address = "0x1c090000"
     smmu_base_address = "0x2b400000"
     smmu_memory_size = "0x100000"
-    enable_vhe = "1"
     enable_mte = "1"
     plat_log_level = "LOG_LEVEL_INFO"
   }
@@ -95,7 +94,6 @@
     pl011_base_address = "0x1c090000"
     smmu_base_address = "0x2b400000"
     smmu_memory_size = "0x100000"
-    enable_vhe = "1"
     plat_log_level = "LOG_LEVEL_INFO"
   }
 }
@@ -116,7 +114,6 @@
   toolchain_args = {
     plat_ffa = "//src/arch/aarch64/plat/ffa:hypervisor"
     pl011_base_address = "0x09000000"
-    enable_vhe = "1"
     plat_log_level = "LOG_LEVEL_INFO"
   }
 }
@@ -142,7 +139,6 @@
     secure_world = "1"
     pl011_base_address = "0x09000000"
     hftest_ctrl = "//test/hftest:ctrl_uart"
-    enable_vhe = "1"
     enable_mte = "1"
     plat_log_level = "LOG_LEVEL_INFO"
   }
@@ -196,7 +192,6 @@
     secure_world = "1"
     pl011_base_address = "0x7ff80000"
     enable_mte = "1"
-    enable_vhe = "1"
     plat_log_level = "LOG_LEVEL_INFO"
   }
 }