unify HOST_CFLAGS and HOSTCFLAGS

The top build system sets up HOSTCFLAGS a bit and exports it, but other
places use HOST_CFLAGS instead.  Unify the two as HOSTCFLAGS so that the
values stay in sync.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/board/spc1920/config.mk b/board/spc1920/config.mk
index e361694..8dacc17 100644
--- a/board/spc1920/config.mk
+++ b/board/spc1920/config.mk
@@ -31,5 +31,5 @@
 #TEXT_BASE = 0xFE000000
 TEXT_BASE = 0xFFF00000
 PLATFORM_CPPFLAGS += -I$(TOPDIR)/board/spc1920
-HOST_CFLAGS += -I$(TOPDIR)/board/spc1920
+HOSTCFLAGS += -I$(TOPDIR)/board/spc1920
 HOST_ENVIRO_CFLAGS += -I$(TOPDIR)/board/spc1920