refactor(libc): clean up dependencies in libc

- Removing platform dependencies from libc modules.
- Replacing panicking with actual error handling.
- Debug macros are included indirectly from assert.h. Removing
  "platform_def.h" from assert.h and adding "common/debug.h"
  where the macros are used.
- Removing hack for fixing PLAT_LOG_LEVEL_ASSERT to 40.
  Instead removing assert with expression, as this
  does not provide additional information.

Signed-off-by: Claus Pedersen <claustbp@google.com>
Change-Id: Icc201ea7b63c1277e423c1cfd13fd6816c2bc568
diff --git a/drivers/arm/gic/v3/gicv3_helpers.c b/drivers/arm/gic/v3/gicv3_helpers.c
index f3852d2..446d0ad 100644
--- a/drivers/arm/gic/v3/gicv3_helpers.c
+++ b/drivers/arm/gic/v3/gicv3_helpers.c
@@ -12,6 +12,8 @@
 #include <common/interrupt_props.h>
 #include <drivers/arm/gic_common.h>
 
+#include <platform_def.h>
+
 #include "../common/gic_common_private.h"
 #include "gicv3_private.h"